Electronic Device

ABSTRACT

Provided is an electronic device with high portability and/or high browsability. The electronic device includes first and second support bodies, a first hinge, and a flexible display panel. The first hinge has a first rotation axis and connects the first and second support bodies to each other, and the first and second support bodies are capable of relatively rotating on the first rotation axis. The display panel includes at least first and second portions supported by the first and second support bodies, respectively; the first rotation axis and a first plane including the display surface overlapping with the first portion or a second plane including the display surface overlapping with the second portion are parallel to each other; and each of a distance between the first rotation axis and the first plane or the second plane is greater than zero.

BACKGROUND OF THE INVENTION

This application is a continuation of copending U.S. application Ser.No. 15/443,670, filed on Feb. 27, 2017 which is a continuation of U.S.application Ser. No. 14/629,990, filed on Feb. 24, 2015 (now U.S. Pat.No. 9,588,549 issued Mar. 7, 2017) which are all incorporated herein byreference.

1. Field of the Invention

One embodiment of the present invention relates to a display device, andparticularly relates to a display device which has flexibility and canbe curved. Furthermore, one embodiment of the present invention relatesto an electronic device including a display device.

Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of theinvention disclosed in this specification and the like relates to anobject, a method, or a manufacturing method. Another embodiment of thepresent invention relates to a process, a machine, manufacture, or acomposition of matter. Therefore, specifically, examples of thetechnical field of one embodiment of the present invention disclosed inthis specification include a semiconductor device, a display device, alight-emitting device, a lighting device, a power storage device, amemory device, a driving method thereof, and a manufacturing methodthereof.

2. Description of the Related Art

In recent years, display devices have been expected to be applied to avariety of uses and have become diversified. For example, displaydevices for use in portable electronic devices and the like are requiredto be thin, light, or robust, for example. In addition, novelapplication is required.

In addition, Patent Document 1 discloses a flexible active-matrixlight-emitting device in which an organic EL element and a transistorserving as a switching element are provided over a film substrate.

PRIOR ART REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    2003-174153

SUMMARY OF THE INVENTION

In recent years, browsability of display has been considered to beimproved by enlarging display regions of display devices to display alarger amount of data. However, in applications of portable devices, anenlargement of display devices might entail a reduction in portability.For this reason, high browsability of display and high portability aredifficult to achieve at the same time.

An object of one embodiment of the present invention is to provide anelectronic device with high portability. Another object is to provide anelectronic device with high browsability. Another object is to providean electronic device with high reliability. Another object is to providea novel display device or electronic device.

Note that the descriptions of these objects do not disturb the existenceof other objects. One embodiment of the present invention does not needto achieve all the objects. Objects other than those described abovewill be apparent from the descriptions of the specification and thelike, and objects other than those described above can be derived fromthe descriptions of the specification and the like.

One embodiment of the present invention is an electronic device whichincludes a first support body, a second support body, a first hinge, anda display panel, characterized in that the display panel hasflexibility; the display panel includes a first display surface and asecond display surface; the first hinge has a function of being capableof rotating on a first rotation axis; the first hinge has a function ofbeing capable of connecting the first support body and the secondsupport body to each other; the first support body and the secondsupport body have a function of being capable of relatively rotating onthe first rotation axis; the display panel includes a first portion, asecond portion, and a third portion; the first portion includes aportion supported by the first support body; the second portion includesa portion supported by the second support body; the third portionincludes a portion not fixed to the first support body and the secondsupport body; the first display surface includes a region where thefirst display surface and the first portion overlap with each other; thesecond display surface includes a region where the second displaysurface and the second portion overlap with each other; a first planeincludes a region parallel to the first rotation axis; the first planeis positioned on the same plane as the first display surface; the firstplane is a plane obtained by extending the first display surface in adirection parallel to the first display surface; the first planeincludes a region where the first plane and the first rotation axisoverlap with each other; the second plane includes a region parallel tothe first rotation axis; the second plane is positioned on the sameplane as the second display surface; the second plane is a planeobtained by extending the second display surface in a direction parallelto the second display surface; the second plane includes a region wherethe second plane and the first rotation axis overlap with each other; adistance between the first plane and the first rotation axis is greaterthan zero; and a distance between the second plane and the firstrotation axis is greater than zero.

In addition, one embodiment of the present invention is an electronicdevice which includes a first support body, a second support body, afirst hinge, and a display panel. The display panel includes a firstportion supported by the first support body, a second portion supportedby the second support body, and a third portion that is positionedbetween the first portion and the second portion and has flexibility.The display panel includes a display surface overlapping with the firstportion, the second portion, and the third portion. The first hinge hasa first rotation axis and has a function of connecting the first supportbody and the second support body to each other. The first support bodyand the second support body have a function of relatively rotating onthe first rotation axis. It is characterized in that the first rotationaxis and a first plane including the display surface overlapping withthe first portion are parallel to each other; the first rotation axisand a second plane including the display surface overlapping with thesecond portion are parallel to each other; a distance between the firstplane and the first rotation axis is greater than zero; and a distancebetween the second plane and the first rotation axis is greater thanzero.

In the above, it is preferable that the distance between the first planeand the first rotation axis be greater than or equal to 0.1 mm and lessthan or equal to 20 mm and the distance between the second plane and thefirst rotation axis be greater than or equal to 0.1 mm and less than orequal to 20 mm.

In the above, it is also preferable that the distance between the firstplane and the first rotation axis and the distance between the secondplane and the first rotation axis be substantially equal to each other.

In the above, it is also preferable that the first support body and thesecond support body be capable of relatively rotating on the firstrotation axis by an angle greater than 180 degrees.

In the above, it is also preferable that the first rotation axis bepositioned on a side in a direction of a normal vector to the firstdisplay surface when the first plane and the second plane are identicalwith each other, and that the display panel be foldable so that a thirddisplay surface overlapping with the third portion becomes a concavesurface. Alternatively, it is preferable that the first rotation axis bepositioned on a side opposite to the direction of the normal vector tothe first display surface when the first plane and the second plane areidentical with each other, and that the display panel be foldable sothat the third display surface overlapping with the third portionbecomes a convex surface.

In the above, it is also preferable that a third support body and asecond hinge be further included; the second hinge have a function ofbeing capable of rotating on a second rotation axis; the second hingehave a function of being capable of connecting the second support bodyand the third support body to each other; the second support body andthe third support body have a function of being capable of relativelyrotating on the second rotation axis; the display panel include a fourthportion and a fifth portion; the display panel include a fourth displaysurface; the fourth portion include a portion supported by the thirdsupport body; the fifth portion include a portion not fixed to thesecond support body and the third support body; the fourth displaysurface include a region where the fourth display surface and the fourthportion overlap with each other; the second plane include a regionparallel to the second rotation axis; a third plane include a regionparallel to the second rotation axis; the third plane be positioned onthe same plane as the fourth display surface; the third plane be a planeobtained by extending the fourth display surface in a direction parallelto the fourth display surface; the third plane include a region wherethe third plane and the second rotation axis overlap with each other; adistance between the second plane and the second rotation axis begreater than zero; and a distance between the third plane and the secondrotation axis be greater than zero.

Alternatively, it is preferable that a third support body and a secondhinge be further included in a structure; the second hinge have a secondrotation axis and have a function of connecting the second support bodyand the third support body to each other; the second support body andthe third support body have a function of relatively rotating on thesecond rotation axis; the display panel include a fourth portionsupported by the third support body and a fifth portion that ispositioned between the second portion and the fourth portion and hasflexibility; the display surface include a portion overlapping with thefourth portion and the fifth portion; the second rotation axis and athird plane including the display surface overlapping with the fourthportion be parallel to each other; the second plane and the secondrotation axis be parallel to each other; a distance between the secondplane and the second rotation axis be greater than zero; and a distancebetween the third plane and the second rotation axis be greater thanzero.

In the above, it is also preferable that the distance between the secondplane and the second rotation axis be greater than or equal to 0.1 mmand less than or equal to 20 mm and the distance between the third planeand the second rotation axis be greater than or equal to 0.1 mm and lessthan or equal to 20 mm.

In the above, it is also preferable that the distance between the secondplane and the second rotation axis and the distance between the thirdplane and the second rotation axis be substantially equal to each other.

In the above, it is also preferable that the second support body and thethird support body be capable of relatively rotating on the secondrotation axis by an angle greater than 180 degrees.

In the above, it is also preferable that the second rotation axis bepositioned on a side in a direction of a normal vector to the seconddisplay surface when the second plane and the third plane are identicalwith each other when the second plane and the third plane are identicalwith each other, and that the display panel be foldable so that a fifthdisplay surface overlapping with the fifth portion becomes a concavesurface. Alternatively, it is preferable that the second rotation axisbe positioned on a side opposite to the direction of the normal vectorto the second display surface when the second plane and the third planeare identical with each other, and that the display panel be foldable sothat the fifth display surface overlapping with the fifth portionbecomes a convex surface.

An electronic device with high portability can be provided.Alternatively, an electronic device with high browsability can beprovided. Alternatively, an electronic device with high reliability canbe provided. Alternatively, a novel display device or electronic devicecan be provided. Note that the descriptions of these effects do notdisturb the existence of other effects. Note that one embodiment of thepresent invention does not necessarily need to have all the aboveeffects. Note that effects other than these will be apparent from thedescriptions of the specification, drawings, claims, and the like, andeffects other than these can be derived from the descriptions of thespecification, drawings, claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C show structure examples of an electronic device accordingto an embodiment.

FIGS. 2A to 2C show structure examples of an electronic device accordingto an embodiment.

FIGS. 3A to 3C show structure examples of an electronic device accordingto an embodiment.

FIGS. 4A to 4C show structure examples of an electronic device accordingto an embodiment.

FIGS. 5A to 5C show structure examples of an electronic device accordingto an embodiment.

FIG. 6 shows a structure example of an electronic device according to anembodiment.

FIGS. 7A to 7C show structure examples of an electronic device accordingto an embodiment.

FIGS. 8A to 8D show structure examples of an electronic device accordingto an embodiment.

FIGS. 9A to 9C show structure examples of an electronic device accordingto an embodiment.

FIGS. 10A to 10B show structure examples of an electronic deviceaccording to an embodiment.

FIGS. 11A to 11D show diagrams illustrating examples of light-emittingpanels according to an embodiment.

FIGS. 12A to 12E show diagrams illustrating examples of light-emittingpanels according to an embodiment.

FIGS. 13A to 13C show diagrams illustrating a manufacturing methodexample of a light-emitting panel according to an embodiment.

FIGS. 14A to 14C show diagrams illustrating a manufacturing methodexample of a light-emitting panel according to an embodiment.

FIGS. 15A to 15C show diagrams illustrating an example of a touch panelaccording to an embodiment.

FIGS. 16A to 16B show diagrams illustrating an example of a touch panelaccording to an embodiment.

FIGS. 17A to 17C show diagrams illustrating an example of a touch panelaccording to an embodiment.

FIGS. 18A to 18C show diagrams illustrating examples of touch panelsaccording to an embodiment.

FIGS. 19A to 19B show a block diagram and a timing chart for a touchsensor according to an embodiment.

FIG. 20 shows a circuit diagram of a touch sensor according to anembodiment.

FIGS. 21A to 21B show a block diagram and a timing chart for a displaydevice according to an embodiment.

FIGS. 22A to 22D show diagrams illustrating operations of a displaydevice and a touch sensor according to an embodiment.

FIGS. 23A to 23D show diagrams illustrating operations of a displaydevice and a touch sensor according to an embodiment.

FIG. 24 shows a block diagram of a touch panel according to anembodiment.

FIGS. 25A to 25B show circuit diagrams of pixels according to anembodiment.

FIG. 26 shows a timing chart illustrating operation of a display deviceaccording to an embodiment.

FIGS. 27A to 27C show photographs of an electronic device according toan example.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the following description,and it will be easily understood by those skilled in the art thatvarious changes can be made without departing from the spirit and scopeof the present invention. Therefore, the present invention should not beconstrued as being limited to the description in the followingembodiments.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and repetitive descriptionthereof is omitted. Furthermore, the same hatch pattern is applied tosimilar functions, and these are not especially denoted by referencenumerals in some cases.

Note that in each drawing described in this specification, the size, thelayer thickness, or the region of each component is exaggerated forclarity in some cases. Therefore, it is not necessarily limited to suchscales.

Note that ordinal numbers such as “first” and “second” in thisspecification and the like are used in order to avoid confusion amongcomponents, and do not limit the components numerically.

Note that in this specification and the like, a plane A being parallelto a plane B means a state in which an angle between a normal to theplane A and a normal to the plane B is greater than or equal to −20° andless than or equal to 20°. In addition, in this specification and thelike, a plane C being perpendicular to the plane B means a state inwhich an angle between a normal to the plane C and the normal to theplane B is greater than or equal to 70° and less than or equal to 110°.In addition, in this specification and the like, a line D beingperpendicular to the plane B means a state in which an angle between theline D and the normal to the plane B is greater than or equal to −20°and less than or equal to 20°. In addition, in this specification andthe like, a line E being parallel to the plane B means a state in whichan angle between the line E and the normal to the plane B is greaterthan or equal to 70° and less than or equal to 110°.

Embodiment 1

In this embodiment, a structure example of an electronic device in oneembodiment of the present invention will be described with reference todrawings.

STRUCTURE EXAMPLE 1

FIG. 1A is a perspective view of an electronic device 100 described inthis structure example. The electronic device 100 includes a displaypanel 101, a support body 102 a, a support body 102 b, and a hinge 103.

The support body 102 a and the support body 102 b are connected by thehinge 103. The support body 102 a and the support body 102 b can berelatively rotated on a rotation axis 111 of the hinge 103. In thestructure example illustrated in FIG. 1A, the support body 102 a and thesupport body 102 b can be relatively rotated on the rotation axis 111 byan angle greater than or equal to 180° from a state where the supportbody 102 a and the support body 102 b are set horizontal.

Here, the rotation axis 111 of the hinge 103 refers to a straight linecorresponding to a rotation axis of a rotation mechanism of the hinge103. For example, in the case where the hinge 103 has a mechanism torotate on an axis of a spindle or the like that is a tangible object, astraight line corresponding to an extending direction of the axis is therotation axis 111.

The display panel 101 includes a display surface where an image or thelike to be viewed by a user is displayed. Note that in thisspecification and the like, the display surface refers to a surface of adisplay panel on a side where an image or the like is displayed.

The display panel 101 has flexibility at least partly. Therefore, thedisplay panel 101 can be reversibly changed in shape from a state wherethe display surface is planar into a state where it has a curvedsurface. The display panel 101 has flexibility at least in a portionwhich is changed in shape with a change in the relative position of thetwo support bodies, and does not necessarily have flexibility in otherportions.

Furthermore, part of the display panel 101 is supported by the supportbody 102 a and another part thereof is supported by the support body 102b.

The electronic device 100 of one embodiment of the present invention hasa structure in which the display panel 101 having flexibility issupported by two support bodies. The display panel 101 can be changed inshape by bending or the like. For example, the display panel 101 can bebent so that the display surface faces inward (bent inward). The displaypanel 101 can also be folded by bending. The electronic device 100 ofone embodiment of the present invention has high portability with thedisplay panel 101 folded, and has high browsability with a seamlesslarge display region in an opened state.

FIG. 1B is a schematic diagram illustrating each region (also referredto as portion) of the display panel 101. The display panel 101 has aportion 101 a supported by the support body 102 a in a portionoverlapping with the support body 102 a. In addition, the display panel101 has a portion 101 b supported by the support body 102 b in a portionoverlapping with the support body 102 b. Furthermore, the display panel101 has a portion 101 c not fixed to either of the support bodiesbetween the portion 101 a and the portion 101 b.

In the portion 101 a, the display panel 101 is preferably supported bythe support body 102 a such that the display surface of the displaypanel 101 is planar. Similarly, in the portion 101 b, the display panel101 is preferably supported by the support body 102 b such that thedisplay surface of the display panel 101 is horizontal.

In addition, the display panel 101 is preferably supported by eachsupport body so as to slide in a direction parallel to a bendingdirection. For example, the display panel 101 is preferably supported byeach support body such that its position in the thickness direction isfixed. At this time, it is preferable that the display panel 101 canslide in the bending direction of the directions parallel to the displaysurface and its position in a direction perpendicular thereto be fixed.By using such a supporting method, when the support bodies arerelatively rotated from a state in which the display panel 101 is setplanar into a state in which it is bent by 180°, a slight difference inthe length of the display panel 101 between the two states can becorrected by the slide operation, whereby damage to the display panel101 can be reduced. Alternatively, one of the plurality of supportbodies and the display panel 101 may be fixed to each other such thatthe display panel 101 does not slide. Furthermore, part of the displaypanel 101 may have elasticity. Expansion and contraction of part of thedisplay panel 101 can correct the above difference in length.Furthermore, the display panel 101 may be fixed to each support bodysuch that the portion 101 c of the display panel 101 loosens in thestate where the display panel 101 is opened. By the looseness of thedisplay panel 101, the above difference in length can be corrected.

A method for supporting the display panel 101 with each support body isnot particularly limited. For example, by using a method in which thedisplay panel 101 is sandwiched between two members that are processedsuch that grooves in which the display panel 101 can be fitted areformed, the display panel 101 can be supported so as to slide. In thecase where the display panel 101 and each support body are fixed to eachother, examples include an attaching method, a fixing method with screwsor the like, a mechanically fixing method in which the display panel 101is sandwiched between members, and the like.

In addition, the areas of the portion 101 a and the portion 101 b arenot particularly limited, and the display panel 101 includes at leasttwo regions supported by respective support bodies and one or moreregions not supported by (fixed to) either of the support bodiestherebetween. For example, the display panel 101 may be supported in aregion overlapping with an edge of each support body, and the entirevisible region may be the portion 101 c not supported by the supportbodies.

FIG. 1C is a schematic cross-sectional view along cutting-plane lineA1-A2 in FIG. 1A. In addition, in FIG. 1C, the hinge 103 is indicated bya broken line in order to show the positional relationship between eachcomponent and the hinge 103.

Each of FIGS. 1A to 1C illustrates the case where the support body 102 aand the support body 102 b are positioned so that the entire displaysurface of the display panel 101 is set planar, in other words, the casewhere a first plane 110 a including the display surface in the portion101 a of the display panel 101 and a second plane 110 b including thedisplay surface in the portion 101 b of the display panel 101 areparallel to each other.

At this time, the rotation axis 111 of the hinge 103 is provided so asto overlap with the portion 101 c of the display panel 101 (i.e., so asto be positioned over the portion 101 c). Furthermore, as illustrated inFIG. 1C, a distance between the rotation axis 111 and the displaysurface is preferably provided so as to be apart from each other by adistance r₀ to prevent the rotation axis 111 of the hinge 103 and thedisplay surface of the display panel 101 from corresponding to eachother (i.e., to prevent the rotation axis 111 from being positioned in aplane including the display surface). That is, the hinge 103 ispreferably provided so that each of the distance between the first plane110 a and the rotation axis 111 and the distance between the secondplane 110 b and the rotation axis 111 has a value greater than zero.Furthermore, when the first plane 110 a and the second plane 110 b areidentical with each other (i.e., positioned on the same plane), therotation axis 111 is provided on a display surface side of the displaypanel 101 (specifically, a side in a direction of a normal vector to thedisplay surface) so as to be in a position apart from the displaysurface.

Furthermore, as illustrated in FIG. 1C, it is preferable that thedisplay surface of the display panel 101 and the rotation axis 111 beparallel to each other. That is, it is preferable that the first plane110 a and the rotation axis 111 be parallel to each other and the secondplane 110 b and the rotation axis 111 be parallel to each other.

Note that there may be a case where a plane including the displaysurface (here, a plane including the first plane 110 a and the secondplane 110 b) and the rotation axis 111 are not exactly parallel to eachother when the display surface of the display panel 101 is set planar.At this time, it is acceptable as long as the first plane 110 a or thesecond plane 110 b and the rotation axis 111 do not intersect with eachother at least in a region overlapping with the display surface of thedisplay panel 101. Note that in the case where the plane including thedisplay surface and the rotation axis 111 are not exactly parallel toeach other (i.e., in the case where the angle between the normaldirection to the display surface and the rotation axis 111 is notexactly 90°), the distance r₀ between the rotation axis 111 and thedisplay surface (or the first plane 110 a or the second plane 110 b) canbe a distance r₀ having the smallest value between the display surface(or the first plane 110 a or the second plane 110 b) and a lineoverlapping with the display surface of the display panel 101 on astraight line including the rotation axis 111.

FIG. 2A is a schematic perspective view of the electronic device 100 ina state where the support body 102 b is rotated on the rotation axis 111by 180° to the support body 102 a. In addition, FIG. 2B is a schematiccross-sectional view along cutting-plane line B1-B2 in FIG. 2A.Furthermore, FIG. 2C is an enlarged schematic cross-sectional view of aregion enclosed by a broken line in FIG. 2B.

As illustrated in FIGS. 2B and 2C, the display panel 101 has a portionwhere the display surface in the portion 101 c is curved by 180° so asto be concave. In addition, the first plane 110 a including part of thedisplay surface in the portion 101 a of the display panel 101 and theplane 110 b including part of the display surface in the portion 101 bare parallel to each other.

At this time, the distance between the first plane 110 a and therotation axis 111 and the distance between the second plane 110 b andthe rotation axis 111 are preferably set to the same distance (r₀). Whenthese distances are equal, the entire display surface of the displaypanel 101 can be set flat (planar) with no step (level difference)generated on the surface of the display panel 101 positioned between thesupport body and the support body, in a state where the two supportbodies are opened as illustrated in FIGS. 1A to 1C. Accordingly, theelectronic device 100 with high visibility can be realized.

Part of the portion 101 c of the display panel 101 is curved dependingon the angle made by the two support bodies. Furthermore, each of thetwo support bodies rotates on the rotation axis 111 while beingsupported by the hinge 103. Therefore, the direction of force to whichthe portion 101 c of the display panel 101 is subjected when the anglebetween the two support bodies is changed is a direction parallel to therotation direction of the support bodies, in other words, a directionperpendicular to a contact surface between each support body and thedisplay panel 101. That is, most components of force applied to theportion 101 c of the display panel 101 are in a direction parallel tothe thickness direction of the display panel 101, that is, a directionin which the display panel 101 is curved. Therefore, the display panel101 is not subjected to excessive force; thus, damage to the curvedportion of the display panel 101 can be effectively reduced.

In addition, as illustrated in FIG. 2C, when the first plane 110 a andthe second plane 110 b are parallel to each other, the curvature radiusr₁ of the curved portion of the display panel 101 is substantially equalto the distance r₀.

FIG. 3A is a schematic perspective view of the electronic device 100 ina state where the support body 102 b is rotated on the rotation axis 111by an angle greater than 180° to the support body 102 a. In addition,FIG. 3B is a schematic cross-sectional view along cutting-plane lineC1-C2 in FIG. 3A. Furthermore, FIG. 3C is an enlarged schematiccross-sectional view of a region enclosed by a broken line in FIG. 3B.

Each of FIGS. 3A to 3C illustrates a state where the support body 102 aand the support body 102 b are rotated such that respective end portionsof the two support bodies on sides opposite to the hinge 103 are incontact with each other.

As illustrated in FIG. 3C, when the two support bodies are rotated by anangle greater than 180° from a state where the display panel 101 is setflat, the curvature radius r₁ of the portion 101 c of the display panel101 is smaller than the distance r₀ between the first plane 110 a (orthe second plane 110 b) and the rotation axis 111 of the hinge 110.

Here, the curvature radius r₁ of the curved portion of the display panel101 refers to a curvature radius of the curved display surface which hasthe smallest value. As the angle of rotation from the state where thedisplay panel 101 is set flat increases, the value of the curvatureradius r₁ with respect to the distance r₀ decreases. For example, thecurvature radius r₁ at a rotation angle of 185° is approximately 0.93times the distance r₀, the curvature radius r₁ at a rotation angle of190° is approximately 0.87 times the distance r₀, and the curvatureradius r₁ at a rotation angle of 195° is approximately 0.82 times thedistance r₀.

When the angle of rotation from the state where the display panel 101 isset flat is greater than 180° , the thickness of the electronic device100 in a state where the two support bodies are folded can be partiallysmall; thus, the electronic device with high portability can berealized. For example, the maximum value of the rotation angle may beset in a range greater than 180° and less than or equal to 200°,preferably greater than 180° and less than or equal to 195°, morepreferably greater than 180° and less than or equal to 190°.

Damage to the curved portion of the display panel 101 can be reduced bysetting the distance r₀ between the first plane 110 a (or the secondplane 110 b) and the rotation axis 111 of the hinge 110 in view of themaximum value of the rotation angle and the minimum curvature radiusallowable to the display panel 101.

For example, when the distance between the first plane 110 a and therotation axis 111 and the distance between the second plane 110 b andthe rotation axis 111 are equal to each other and are each r₀, the valueof r₀ is preferably set larger than or equal to 0.1 mm and smaller thanor equal to 20 mm, preferably larger than or equal to 0.5 mm and smallerthan or equal to 15 mm, more preferably larger than or equal to 1 mm andsmaller than or equal to 10 mm, and is typically preferably set to 4 mm.As r₀ decreases, the thickness of the electronic device 100 in the statewhere the support bodies are folded can be reduced; thus, the electronicdevice 100 with high portability can be realized.

Furthermore, the thickness of the display panel 101 is preferably largerthan or equal to 5 μm and smaller than or equal to 2000 μm, preferablylarger than or equal to 5 μm and smaller than or equal to 1000 μm, morepreferably larger than or equal to 10 82 m and smaller than or equal to500 μm, further preferably larger than or equal to 20 μm and smallerthan or equal to 300 μm. As the thickness of the display panel 101decreases, the minimum allowable curvature radius can be decreased;thus, the thickness of the electronic device 100 can be decreased.

In the case where the display panel 101 is too thin to have a sufficientmechanical strength, the strength may be supplemented by attaching asheet having flexibility or the like to at least the curving portion ofthe display panel 101. For example, besides an elastic body of hardrubber or the like, plastic, a metal such as aluminum, an alloy such asstainless steel or a titanium alloy, rubber such as silicone rubber, orthe like can be used. A material having lower flexibility than thedisplay panel 101 is preferably used for the sheet. In the case wherethe sheet does not have a light transmitting property, it may be placedon a back surface side of the display panel 101 or in a region outside adisplay region of the display surface. A structure may be employed inwhich a sheet having an opening in a portion overlapping with thedisplay surface is placed on a display surface side and the displaypanel is sandwiched between two sheets.

The curvature radius r₁ in the state where the two support bodies arefolded, i.e., a state where the curved portion of the display panel 101is curved with the smallest curvature radius, is preferably set largerthan or equal to 0.1 mm and smaller than or equal to 20 mm, preferablylarger than or equal to 0.5 mm and smaller than or equal to 15 mm, morepreferably larger than or equal to 1 mm and smaller than or equal to 10mm, and is typically preferably set smaller than or equal to 4 mm.

Here, a module including a touch sensor is preferably provided by beingstacked on the display surface side of the display panel 101. At thistime, it is preferable that at least part of the module including thetouch sensor have flexibility and can be curved along the display panel101. At this time, the module including the touch sensor and the displaypanel 101 may be attached to each other with an adhesive or the like, ora polarizing plate or a buffer material (separator) may be providedtherebetween. In addition, the thickness of the module including thetouch sensor is preferably smaller than or equal to the thickness of thedisplay panel 101.

Alternatively, the display panel 101 may function as a touch panel. Forexample, a structure of an on-cell touch panel or an in-cell touch panelmay be employed as the display panel 101. By using the structure of theon-cell or in-cell touch panel, the thickness can be reduced even whenthe function of a touch panel is added to the display panel 101.

In addition, the structure of the hinge 103 is not limited to thestructure illustrated in FIGS. 1A to 1C or the like, and ones in avariety of modes can be used. Furthermore, part of the support body 102a or the support body 102 b may have a mode of functioning as the hinge103. Moreover, although a pair of hinges 103 are provided in thestructure of FIGS. 1A to 1C or the like, one hinge or three or morehinges may be provided.

Note that electronic components, for example, a battery, a printedwiring board on which a variety of ICs such as an arithmetic device anda driver circuit are mounted, a wireless receiver, a wirelesstransmitter, a wireless power receiver, and a variety of sensors such asan acceleration sensor are incorporated as appropriate into one of thesupport body 102 a and the support body 102 b, or both, so that theelectronic device 100 can function as a portable terminal, a portableimage reproducing device, a portable lighting device, or the like. Acamera, a speaker, a variety of input/output terminals such as a powersupply terminal and a signal supply terminal, a variety of sensors suchas an optical sensor, an operation button, or the like may also beincorporated into one of the support body 102 a and the support body 102b, or both.

The above is the description of the structure example 1.

STRUCTURE EXAMPLE 2

A structure example of an electronic device 120 whose structure ispartly different from the above structure example 1 will be describedbelow. Note that description of portions overlapping with those in thestructure example 1 may be omitted in some cases.

FIG. 4A is a perspective view of a display surface side of theelectronic device 120, and FIG. 4B is a perspective view of a backsurface side. In addition, FIG. 4C is a schematic cross-sectional viewalong cutting-plane line D1-D2 in FIG. 4A.

The electronic device 120 differs from the electronic device 100exemplified in the above structure example 1 mainly in that the positionof the hinge 103 is different and in that the shapes of the support body102 a and the support body 102 b are different.

The electronic device 120 of one embodiment of the present invention hasa structure in which the display panel 101 having flexibility issupported by two support bodies. The display panel 101 can be changed inshape by bending or the like. For example, the display panel 101 can bebent so that a display surface faces outward (bent outward). The displaypanel 101 can also be folded by bending. The electronic device 120 ofone embodiment of the present invention has high portability with thedisplay panel 101 folded, and has high browsability of display with aseamless large display region in an opened state.

The hinge 103 is provided such that the rotation axis 111 thereof ispositioned on a side opposite to the display surface of the displaypanel 101. In a structure illustrated in FIGS. 4A to 4C, the hinge 103is provided on a side opposite to surfaces of the support body 102 a andthe support body 102 b where the display panel 101 is provided.Furthermore, when the first plane 110 a including the display surface inthe portion 101 a of the display panel 101 and the second plane 110 bincluding the display surface in the portion 101 b of the display panel101 are identical with each other, the rotation axis 111 is provided ona side opposite to the display surface of the display panel 101(specifically, a side opposite to a direction of a normal vector to thedisplay surface) so as to be in a position apart from the displaysurface.

In addition, the support body 102 a and the support body 102 b have acut-out portion at least in a region overlapping with the portion 101 cof the display panel 101. In FIG. 4C, a portion overlapping with thesupport body 102 a of the display panel 101 is the portion 101 a, aportion overlapping with the support body 102 b is the portion 101 b,and a portion overlapping with the cut-out portion is the portion 101 c.Note that the entire portion overlapping with the support body 102 a (orthe support body 102 b) in the display panel 101 does not need to besupported by the support body 102 a (or the support body 102 b) and itis acceptable as long as it is partly supported as in the structureexample 1.

The support body 102 a and the support body 102 b can be relativelyrotated on the rotation axis 111 by an angle greater than or equal to180° so that the display surface in the portion 101 c of the displaypanel 101 becomes convex.

FIG. 5A is a schematic perspective view of the electronic device 120 ina state where the support body 102 b is rotated on the rotation axis 111by 180° to the support body 102 a. In addition, FIG. 5B is a schematiccross-sectional view along cutting-plane line E1-E2 in FIG. 5A.Furthermore, FIG. 5C is an enlarged schematic cross-sectional view of aregion enclosed by a broken line in FIG. 5B.

As illustrated in each of FIGS. 5A to 5C, the display panel 101 iscurved such that part of the display surface in the portion 101 c ischanged in shape so as to be convex. At this time, the cut-out portionprovided in the support body 102 a and the support body 102 b allows thedisplay panel 101 to be curved without physical interference of thedisplay panel 101 and each support body with each other.

Note that a structure may be employed in which back surface sides of thesupport body 102 a and the support body 102 b are in contact with eachother when the display panel 101 is bent 180° as illustrated in FIG. 6.

FIG. 7A is a schematic perspective view of the electronic device 120 ina state where the support body 102 b is rotated on the rotation axis 111by an angle greater than 180° to the support body 102 a. In addition,FIG. 7B is a schematic cross-sectional view along cutting-plane lineF1-F2 in FIG. 7A. Furthermore, FIG. 7C is an enlarged schematiccross-sectional view of a region enclosed by a broken line in FIG. 7B.

When the two support bodies are thus rotated by an angle greater than180° from a state where the display panel 101 is set flat, the thicknessof the electronic device 120 in a state where the two support bodies arefolded can be partially small; thus, the electronic device with highportability can be realized.

As illustrated in FIG. 7C, when the two support bodies are rotated by anangle greater than 180° from the state where the display panel 101 isset flat, the curvature radius r₁ of the portion 101 c of the displaypanel 101 is smaller than the distance r₀ between the first plane 110 a(or the second plane 110 b) and the rotation axis 111 of the hinge 110.

The above is the description of the structure example 2.

STRUCTURE EXAMPLE 3

A structure example of an electronic device 130 whose structure ispartly different from the above structure example will be describedbelow. Note that description of portions overlapping with those in theabove structure example may be omitted in some cases.

FIG. 8A is a perspective view of a display surface side of theelectronic device 130, and FIG. 8B is a perspective view of a backsurface side.

The electronic device 130 differs mainly in including a support body 102c in addition to the electronic device 120 exemplified in the structureexample 2.

The support body 102 a and the support body 102 b are connected to eachother by a hinge 103 a. The support body 102 b and the support body 102c are connected to each other by a hinge 103 b. The display panel 101includes regions supported by the support body 102 a, the support body102 b, and the support body 102 c, respectively. In addition, thedisplay panel 101 includes regions not supported by the support bodiesbetween the region supported by the support body 102 a and the regionsupported by the support body 102 b and between the region supported bythe support body 102 b and the region supported by the support body 102c.

The electronic device 130 of one embodiment of the present invention hasa structure in which the display panel 101 having flexibility is partlysupported by three support bodies. The electronic device 130 includes aregion where the display panel 101 can be bent so that a display surfacefaces inward (bent inward) and a region where the display panel 101 canbe bent so that the display surface faces outward (bent outward).

The display panel 101 can also be folded by bending. The electronicdevice 130 of one embodiment of the present invention has highportability with the display panel 101 folded, and has high browsabilityof display with a seamless large display region in an opened state.

When the display surface of the display panel 101 is set planar asillustrated in FIG. 8A, a rotation axis 111 a of the hinge 103 a isprovided so as to be positioned on a side opposite to the displaysurface as in the structure example 2. In addition, at this time, arotation axis 111 b of the hinge 103 b is provided so as to bepositioned on a display surface side as in the structure example 1.

The support body 102 a and the support body 102 b can be relativelyrotated on the rotation axis 111 a of the hinge 103 a by an anglegreater than or equal to 180° so that the display surface of the displaypanel 101 becomes convex as in the structure example 2.

The support body 102 b and the support body 102 c can be relativelyrotated on the rotation axis 111 b of the hinge 103 b by an anglegreater than or equal to 180° so that the display surface of the displaypanel 101 becomes concave as in the structure example 1.

By relatively rotating the support bodies on the rotation axis 111 a andthe rotation axis 111 b, the electronic device 130 can be changed inshape into a folded state illustrated in FIG. 8D through the modeillustrated in FIG. 8C.

As illustrated in FIG. 8D, the support body 102 a and the support body102 c can be set parallel to each other by folding the electronic device130 such that an angle made by facing planes of the support body 102 aand the support body 102 b and an angle made by facing planes of thesupport body 102 b and the support body 102 c are equal to each other.This is preferable because the thickness of the electronic device 130 inthe folded state can be uniform.

In addition, the thickness of the electronic device 130 can be reducedby folding the electronic device 130 such that both the above two anglesare acute angles as illustrated in FIG. 8D, as compared with the casewhere the three support bodies are set parallel.

To use the electronic device 130 of one embodiment of the presentinvention, the display panel 101 may be opened as illustrated in FIG. 8Aso that the entire display surface can be used as a seamless largedisplay surface , or part of the display surface can be used in thefolded state as illustrated in FIG. 8D. When the display panel 101 isfolded inward, part of the display surface that is hidden from a user isput in a non-display (non-operation) state, leading to a reduction inpower consumption of the display panel 101.

Furthermore, only the support body 102 a may be rotated to a back sideto use part of the display surface overlapping with the support body 102b and the support body 102 c. At this time, a portion of the displaysurface which overlaps with the support body 102 a may display an imageor the like or may be put in a non-display (non-operation) state. Thisportion can also be used as a touch pad.

A convexly curved portion of the display surface can displaynotification of an incoming e-mail, SNS (social networking service),call, or the like; a subject of an e-mail, an SNS, or the like; a senderof an e-mail, an SNS, or the like; the date; the time; remainingbattery; the reception strength of an antenna; and the like.Alternatively, an image having a function of an operation button, anicon, a slider, or the like may be displayed.

In addition, the display surface of the display panel 101 is preferablyset to have a predetermined aspect ratio in an opened state (e.g., thestate illustrated in FIG. 8A). For example, the aspect ratio is set to9:16 or the like. In addition, the display panel 101 in the folded state(e.g., the state illustrated in FIG. 8D) is preferably set to have avalue close to the aspect ratio in the opened state. This enables theaspect ratios of images displayed in the opened and folded states to besubstantially equal to each other. Accordingly, in the case where thesame image is displayed on the entire display surface visible in theopened and folded states by zooming in or out, generation of anunnatural margin in either state can be reduced.

The above is the description of the structure example 3.

STRUCTURE EXAMPLE 4

A more specific structure example will be described below. Note thatdescription of portions overlapping with those in the above structureexample may be omitted in some cases.

FIG. 9A is a schematic perspective view of an electronic device 140 in astate where the display panel 101 is opened, and FIG. 9B is a schematicperspective view in a state where the display panel 101 is folded.

The electronic device 140 includes the display panel 101, a housing 141,a support body 142 a, a support body 142 b, a support body 142 c, ahinge 143 a, and a hinge 143 b.

The electronic device 140 can be reversibly changed in shape from thestate in FIG. 9A to the state in FIG. 9B by relatively rotating thesupport bodies on a rotation axis 151 a of the hinge 143 a and arotation axis 151 b of the hinge 143 b.

In addition, the electronic device 140 may include an operation button145 or the like. For example, the operation button 145 may have afunction of switching images displayed on the display surface of thedisplay panel 101, a function of controlling turning on and off power, afunction of changing the display panel 101 in shape from the foldedstate to the opened state, or the like.

FIG. 9C is a schematic cross-sectional view along cutting-plane lineG1-G2 illustrated in FIG. 9B. As illustrated in FIG. 9C, the housing 141includes a printed board 144, a battery 149, and the like in the inside.

In addition, a plurality of FPCs 147 electrically connected to thedisplay panel 101 are connected to a plurality of terminal connectionportions 148 of the printed board 144. Furthermore, power is supplied tothe printed board 144 from the battery 149.

As the battery 149, a secondary battery such as a lithium ion battery ispreferably used, for example. In addition, the battery 149 preferablyincludes an antenna and a circuit for controlling charge and dischargeand has a wirelessly rechargeable structure.

On the printed board 144, a battery and a variety of ICs such as anarithmetic device and a driver circuit are mounted. Although notillustrated, electronic components, for example, a wireless receiver, awireless transmitter, a wireless power receiver, and a variety ofsensors such as an acceleration sensor are incorporated as appropriateinto the housing 141, so that the electronic device 140 can function asa portable terminal, a portable image reproducing device, a portablelighting device, or the like. A camera, a speaker, a variety ofinput/output terminals such as a power supply terminal and a signalsupply termianal, a variety of sensors such as an optical sensor, anoperation button, or the like may also be incorporated into the housing141.

Here, as illustrated in FIG. 9A, the thicknesses of the support body 142b and the support body 142 c which do not overlap with the housing 141in a state where the display panel 101 is opened are preferably small.For example, as illustrated in FIG. 9C, it is preferable that thethicknesses t of the support body 142 b and the support body 142 c beequal and smaller than the thickness of the housing 141. For example,the thicknesses t of the support body 142 b and the support body 142 care preferably larger than or equal to 0.3 mm and smaller than or equalto 10 mm, preferably larger than or equal to 0.3 mm and smaller than orequal to 5 mm, and are typically preferably set to 1 mm. By reducing thethicknesses of the support body 142 b and the support body 142 c, theweight of the electronic device 140 can be reduced, and the portabilitycan be further improved. In addition, when the thicknesses of thesupport body 142 b and the support body 142 c are smaller than that ofthe housing 141, there is a small difference in the position of thecenter of gravity between the opened and folded states; thus, the usewhile supporting only the housing 141 with one hand becomes easy ineither state, leading to improvement in convenience.

The above is the description of the structure example 4.

MODIFICATION EXAMPLE

FIG. 10A illustrates a schematic perspective view of an electronicdevice 160. The electronic device 160 differs mainly in the structuresof the housing 141 and the support body 142 b in the electronic device140 exemplified in FIGS. 9A to 9C.

A housing 161 of the electronic device 160 is thinner than the housing141. Therefore, the electronic device 160 has a structure that is easilygraspable with one hand.

In addition, the support body 142 b of the electronic device 160 has amechanism with which the length between both ends thereof changes (alsoreferred to as a slide mechanism) so that a distance between the supportbody 142 a and the support body 142 c can be changed.

FIG. 10B illustrates a schematic cross-sectional view of the supportbody 142 b and its vicinity. The support body 142 b includes aplate-like member 162 a, a plate-like member 162 b, a plate-like member162 c, and a screw 163.

The member 162 a is connected to the hinge 143 a. The member 162 c isconnected to the hinge 143 b. In addition, the member 162 c has anopening 164. The member 162 a and the member 162 b are provided tooverlap with part of the member 162 c such that the opening 164 of themember 162 c is sandwiched. In addition, the member 162 a and the member162 b are fixed to each other by the screw 163. Furthermore, the member162 a and the member 162 c as well as the member 162 b and the member162 c are not fixed to each other.

With such a structure, the member 162 c can be slid with respect to themember 162 a and the member 162 b in directions of arrows illustrated inthe drawing. Therefore, a distance between the hinge 143 a and the hinge143 b can be variable. In other words, a distance between the supportbody 142 a and the support body 142 c can be changed.

At this time, it is preferable that the display panel 101 be provided soas to be fixed to each of the support body 142 a and the support body142 c and not fixed to the support body 142 b.

With such a structure, a slight difference in the length of the displaypanel 101 which is caused by bending the display panel 101 can becorrected by the slide operation of the support body 142 b.

In the structure illustrated in FIG. 10B, the length to which the member162 c can be displaced is determined by the position of the screw 163and the size of the opening 164. In sliding the member 162 c, the slidestops when an end portion of the opening 164 is brought into contactwith the screw 163.

Note that the structure illustrated in FIGS. 10A and 10B is one example,and any mechanism with which the length between both ends of the supportbody 142 b can be changed is acceptable without limitation to thisstructure. A mechanism with which the distance between the hinge 143 aand the hinge 143 b can be changed may be provided in the electronicdevice 160. Alternatively, a mechanism with which the distance betweenthe support body 142 a and the support body 142 c can be changed may beprovided in the electronic device 160.

At least part of this embodiment can be implemented as appropriate incombination with any of the other embodiments described in thisspecification.

Embodiment 2

In this embodiment, structure examples and a manufacturing methodexample of a light-emitting panel that is applicable to a display panelof the electronic device of one embodiment of the present invention willbe described.

SPECIFIC EXAMPLE 1

FIG. 11A illustrates a plan view of a light-emitting panel, and FIG. 11Cillustrates an example of a cross-sectional view along dashed-dottedline A1-A2 in FIG. 11A. The light-emitting panel described in thespecific example 1 is a top-emission light-emitting panel using a colorfilter method. In this embodiment, the light-emitting panel can employ,for example, a structure in which sub-pixels of three colors of R (red),G (green), and B (blue) express one color, or a structure in whichsub-pixels of four colors of R (red), G (green), B (blue), and W (white)express one color. There is no particular limitation on a color element,and colors other than R, G, B, and W may be used. For example, yellow,cyan, magenta, and the like may be included.

The light-emitting panel illustrated in FIG. 11A includes alight-emitting portion 804, driver circuit portions 806, and an FPC(Flexible Printed Circuit) 808. Light-emitting elements and transistorsincluded in the light-emitting portion 804 and the driver circuitportions 806 are sealed by a substrate 801, a substrate 803, and asealing layer 823.

The light-emitting panel illustrated in FIG. 11C includes the substrate801, an adhesive layer 811, an insulating layer 813, a plurality oftransistors, a conductive layer 857, an insulating layer 815, aninsulating layer 817, a plurality of light-emitting elements, aninsulating layer 821, the sealing layer 823, an overcoat 849, a coloringlayer 845, a light-blocking layer 847, an insulating layer 843, anadhesive layer 841, and the substrate 803. The sealing layer 823, theovercoat 849, the insulating layer 843, the adhesive layer 841, and thesubstrate 803 transmit visible light.

The light-emitting portion 804 includes a transistor 820 and alight-emitting element 830 over the substrate 801 with the adhesivelayer 811 and the insulating layer 813 provided therebetween. Thelight-emitting element 830 includes a lower electrode 831 over theinsulating layer 817, an EL layer 833 over the lower electrode 831, andan upper electrode 835 over the EL layer 833. The lower electrode 831 iselectrically connected to a source electrode or a drain electrode of thetransistor 820. An end portion of the lower electrode 831 is coveredwith the insulating layer 821. The lower electrode 831 preferablyreflects visible light. The upper electrode 835 transmits visible light.

The light-emitting portion 804 also includes the coloring layer 845overlapping with the light-emitting element 830 and the light-blockinglayer 847 overlapping with the insulating layer 821. The coloring layer845 and the light-blocking layer 847 are covered with the overcoat 849.A space between the light-emitting element 830 and the overcoat 849 isfilled with the sealing layer 823.

The insulating layer 815 has an effect of reducing the diffusion ofimpurities into a semiconductor included in the transistor. As theinsulating layer 817, an insulating layer having a planarizationfunction is preferably selected in order to reduce surface unevennessdue to the transistor.

The driver circuit portions 806 include a plurality of transistors overthe substrate 801 with the adhesive layer 811 and the insulating layer813 provided therebetween. FIG. 11C illustrates one of the transistorsincluded in the driver circuit portions 806.

The insulating layer 813 and the substrate 801 are attached to eachother with the adhesive layer 811. In addition, the insulating layer 843and the substrate 803 are attached to each other with the adhesive layer841. It is preferable to use films with low water permeability for theinsulating layer 813 and the insulating layer 843, in which case theentry of an impurity such as water into the light-emitting element 830or the transistor 820 can be reduced, leading to high reliability of thelight-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal (e.g., a video signal, a clock signal, astart signal, or a reset signal) or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example in whichthe FPC 808 is provided as the external input terminal is described. Toprevent an increase in the number of steps, the conductive layer 857 ispreferably formed using the same material and the same step as theelectrode or the wiring in the light-emitting portion or the drivercircuit portion. Here, an example in which the conductive layer 857 isformed using the same material and the same step as the electrodesincluded in the transistor 820 is described.

In the light-emitting panel illustrated in FIG. 11C, a connector 825 ispositioned over the substrate 803. The connector 825 is connected to theconductive layer 857 through an opening provided in the substrate 803,the adhesive layer 841, the insulating layer 843, the sealing layer 823,the insulating layer 817, and the insulating layer 815. The connector825 is also connected to the FPC 808. The FPC 808 and the conductivelayer 857 are electrically connected to each other via the connector825. In the case where the conductive layer 857 and the substrate 803overlap with each other, the conductive layer 857, the connector 825,and the FPC 808 can be electrically connected to one another by formingan opening in the substrate 803 (or using a substrate having anopening).

The specific example 1 describes the light-emitting panel which can bemanufactured by forming the insulating layer 813, the transistor 820,and the light-emitting element 830 over a formation substrate with highheat resistance, separating the formation substrate, and transferringthe insulating layer 813, the transistor 820, and the light-emittingelement 830 to the substrate 801 with the adhesive layer 811. Thespecific example 1 also describes the light-emitting panel which can bemanufactured by forming the insulating layer 843, the coloring layer845, and the light-blocking layer 847 over a formation substrate withhigh heat resistance, separating the formation substrate, andtransferring the insulating layer 843, the coloring layer 845, and thelight-blocking layer 847 to the substrate 803 with the adhesive layer841.

In the case where a material with low heat resistance (e.g., a resin) isused for a substrate, it is difficult to expose the substrate to hightemperatures in the manufacturing process. Thus, there is a limitationon conditions for forming a transistor and an insulating layer over thesubstrate. In addition, in the case where a material with high waterpermeability (e.g., a resin) is used for a substrate, it is preferableto form a film at high temperatures to have low water permeability. Inthe manufacturing method of this embodiment, a transistor and the likecan be formed over a formation substrate with high heat resistance;thus, a highly reliable transistor and a film with sufficiently lowwater permeability can be formed at high temperatures. Then, these aretransferred to the substrate 801 and the substrate 803, whereby a highlyreliable light-emitting panel can be manufactured. Thus, according toone embodiment of the present invention, a lightweight or thin andhighly reliable light-emitting panel can be realized. Details of themanufacturing method will be described later.

SPECIFIC EXAMPLE 2

FIG. 11B illustrates a plan view of a light-emitting panel, and FIG. 11Dillustrates an example of a cross-sectional view along dashed-dottedline A3-A4 in FIG. 11B. The light-emitting panel described in thespecific example 2 is a top-emission light-emitting panel using a colorfilter method, which is different from that in the specific example 1.Portions different from those in the specific example 1 will bedescribed in detail here and the descriptions of portions common to thespecific example 1 will be omitted.

The light-emitting panel illustrated in FIG. 11D is different from thelight-emitting panel illustrated in FIG. 11C in the aspects below.

The light-emitting panel illustrated in FIG. 11D includes a spacer 827over the insulating layer 821. By providing the spacer 827, the distancebetween the substrate 801 and the substrate 803 can be adjusted.

In addition, in the light-emitting panel illustrated in FIG. 11D, thesubstrate 801 and the substrate 803 have different sizes. The connector825 is positioned over the insulating layer 843 and thus does notoverlap with the substrate 803. The connector 825 is connected to theconductive layer 857 through an opening provided in the insulating layer843, the sealing layer 823, the insulating layer 817, and the insulatinglayer 815. Since no opening needs to be provided in the substrate 803,there is no limitation on the material of the substrate 803.

SPECIFIC EXAMPLE 3

FIG. 12A illustrates a plan view of a light-emitting panel, and FIG. 12Cillustrates an example of a cross-sectional view along dashed-dottedline A5-A6 in FIG. 12A. The light-emitting panel described in thespecific example 3 is a top-emission light-emitting panel using aseparate coloring method.

The light-emitting panel illustrated in FIG. 12A includes thelight-emitting portion 804, the driver circuit portion 806, and the FPC808. Light-emitting elements and transistors included in thelight-emitting portion 804 and the driver circuit portion 806 are sealedby the substrate 801, the substrate 803, a frame-like sealing layer 824,and the sealing layer 823.

The light-emitting panel illustrated in FIG. 12C includes the substrate801, the adhesive layer 811, the insulating layer 813, a plurality oftransistors, the conductive layer 857, the insulating layer 815, theinsulating layer 817, a plurality of light-emitting elements, theinsulating layer 821, the sealing layer 823, the frame-like sealinglayer 824, and the substrate 803. The sealing layer 823 and thesubstrate 803 transmit visible light.

The frame-like sealing layer 824 is preferably a layer having a highergas barrier property than the sealing layer 823. Accordingly, the entryof external moisture or oxygen into the light-emitting panel can bereduced. Thus, the light-emitting panel with high reliability can berealized.

In the specific example 3, light emitted from the light-emitting element830 is extracted from the light-emitting panel through the sealing layer823. Therefore, the sealing layer 823 preferably has a higherlight-transmitting property than the frame-like sealing layer 824. Inaddition, the sealing layer 823 preferably has a higher refractive indexthan the frame-like sealing layer 824. In addition, it is preferablethat a reduction in the volume of the sealing layer 823 by curing besmaller than that of the frame-like sealing layer 824.

The light-emitting portion 804 includes the transistor 820 and thelight-emitting element 830 over the substrate 801 with the adhesivelayer 811 and the insulating layer 813 provided therebetween. Thelight-emitting element 830 includes the lower electrode 831 over theinsulating layer 817, the EL layer 833 over the lower electrode 831, andthe upper electrode 835 over the EL layer 833. The lower electrode 831is electrically connected to the source electrode or the drain electrodeof the transistor 820. The end portion of the lower electrode 831 iscovered with the insulating layer 821. The lower electrode 831preferably reflects visible light. The upper electrode 835 transmitsvisible light.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 801 with the adhesive layer 811 and the insulating layer813 provided therebetween. FIG. 12C illustrates one of the transistorsincluded in the driver circuit portion 806.

The insulating layer 813 and the substrate 801 are attached to eachother with the adhesive layer 811. It is preferable to use a film withlow water permeability for the insulating layer 813, in which case theentry of an impurity such as water into the light-emitting element 830or the transistor 820 can be reduced, leading to high reliability of thelight-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example in whichthe FPC 808 is provided as the external input terminal is described. Inaddition, here, an example in which the conductive layer 857 is formedusing the same material and the same step as the electrodes included inthe transistor 820 is described.

In the light-emitting panel illustrated in FIG. 12C, the connector 825is positioned over the substrate 803. The connector 825 is connected tothe conductive layer 857 through an opening provided in the substrate803, the sealing layer 823, the insulating layer 817, and the insulatinglayer 815. The connector 825 is also connected to the FPC 808. The FPC808 and the conductive layer 857 are electrically connected to eachother via the connector 825.

The specific example 3 describes the light-emitting panel which can bemanufactured by forming the insulating layer 813, the transistor 820,and the light-emitting element 830 over a formation substrate with highheat resistance, separating the formation substrate, and transferringthe insulating layer 813, the transistor 820, and the light-emittingelement 830 to the substrate 801 with the adhesive layer 811. Atransistor and the like can be formed over a formation substrate withhigh heat resistance; thus, a highly reliable transistor and a film withsufficiently low water permeability can be formed at high temperatures.Then, these are transferred to the substrate 801, whereby a highlyreliable light-emitting panel can be manufactured. Thus, according toone embodiment of the present invention, a lightweight or thin andhighly reliable light-emitting panel can be realized.

SPECIFIC EXAMPLE 4

FIG. 12B illustrates a plan view of a light-emitting panel, and FIG. 12Dillustrates an example of a cross-sectional view along dashed-dottedline A7-A8 in FIG. 12B. The light-emitting panel described in thespecific example 4 is a bottom-emission light-emitting panel using acolor filter method.

The light-emitting panel illustrated in FIG. 12D includes the substrate801, the adhesive layer 811, the insulating layer 813, a plurality oftransistors, the conductive layer 857, the insulating layer 815, acoloring layer 845, an insulating layer 817 a, an insulating layer 817b, a conductive layer 816, a plurality of light-emitting elements, theinsulating layer 821, the sealing layer 823, and the substrate 803. Thesubstrate 801, the adhesive layer 811, the insulating layer 813, theinsulating layer 815, the insulating layer 817 a, and the insulatinglayer 817 b transmit visible light.

The light-emitting portion 804 includes the transistor 820, a transistor822, and the light-emitting element 830 over the substrate 801 with theadhesive layer 811 and the insulating layer 813 provided therebetween.The light-emitting element 830 includes the lower electrode 831 over theinsulating layer 817, the EL layer 833 over the lower electrode 831, andthe upper electrode 835 over the EL layer 833. The lower electrode 831is electrically connected to the source electrode or the drain electrodeof the transistor 820. The end portion of the lower electrode 831 iscovered with the insulating layer 821. The upper electrode 835preferably reflects visible light. The lower electrode 831 transmitsvisible light. The position where the coloring layer 845 that overlapswith the light-emitting element 830 is provided is not particularlylimited; for example, it may be provided between the insulating layer817 a and the insulating layer 817 b or between the insulating layer 815and the insulating layer 817 a.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 801 with the adhesive layer 811 and the insulating layer813 provided therebetween. FIG. 12D illustrates two of the transistorsincluded in the driver circuit portion 806.

The insulating layer 813 and the substrate 801 are attached to eachother with the adhesive layer 811. It is preferable to use a film withlow water permeability for the insulating layer 813, in which case theentry of an impurity such as water into the light-emitting element 830or the transistor 820 or 822 can be reduced, leading to high reliabilityof the light-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example in whichthe FPC 808 is provided as the external input terminal is described. Inaddition, here, an example in which the conductive layer 857 is formedusing the same material and the same step as the conductive layer 816 isdescribed.

The specific example 4 describes the light-emitting panel which can bemanufactured by forming the insulating layer 813, the transistor 820,the light-emitting element 830, and the like over a formation substratewith high heat resistance, separating the formation substrate, andtransferring the insulating layer 813, the transistor 820, thelight-emitting element 830, and the like to the substrate 801 with theadhesive layer 811. A transistor and the like can be formed over aformation substrate with high heat resistance; thus, a highly reliabletransistor and a film with sufficiently low water permeability can beformed at high temperatures. Then, these are transferred to thesubstrate 801, whereby a highly reliable light-emitting panel can bemanufactured. Thus, according to one embodiment of the presentinvention, a lightweight or thin and highly reliable light-emittingpanel can be realized.

SPECIFIC EXAMPLE 5

FIG. 12E illustrates an example of a light-emitting panel that isdifferent from those in the specific examples 1 to 4.

The light-emitting panel illustrated in FIG. 12E includes the substrate801, the adhesive layer 811, the insulating layer 813, a conductivelayer 814, a conductive layer 857 a, a conductive layer 857 b, thelight-emitting element 830, the insulating layer 821, the sealing layer823, and the substrate 803.

The conductive layer 857 a and the conductive layer 857 b, which areexternal connection electrodes of the light-emitting panel, can each beelectrically connected to an FPC or the like.

The light-emitting element 830 includes the lower electrode 831, the ELlayer 833, and the upper electrode 835. The end portion of the lowerelectrode 831 is covered with the insulating layer 821. Thelight-emitting element 830 is bottom-emission, top-emission, ordual-emission. An electrode, a substrate, an insulating layer, and thelike on the light extraction side transmit visible light. The conductivelayer 814 is electrically connected to the lower electrode 831.

The substrate on the light extraction side may have, as a lightextraction structure, a hemispherical lens, a micro lens array, a filmprovided with an uneven surface structure, a light diffusing film, orthe like. For example, a light extraction structure can be formed byattaching the above lens or film to a resin substrate with an adhesiveor the like having substantially the same refractive index as thesubstrate, or the lens or film.

The conductive layer 814 is preferably, though not necessarily, providedbecause voltage drop due to the resistance of the lower electrode 831can be reduced. In addition, for a similar purpose, a conductive layerelectrically connected to the upper electrode 835 may be provided overthe insulating layer 821, over the EL layer 833, over the upperelectrode 835, or the like.

The conductive layer 814 can be a single layer or a stacked layer formedusing a material selected from copper, titanium, tantalum, tungsten,molybdenum, chromium, neodymium, scandium, nickel, or aluminum; an alloymaterial containing any of these as its main component; or the like. Thethickness of the conductive layer 814 can be, for example, greater thanor equal to 0.1 μm and less than or equal to 3 μm, preferably greaterthan or equal to 0.1 μm and less than or equal to 0.5 μm.

When a paste (e.g., silver paste) is used as a material for theconductive layer electrically connected to the upper electrode 835,metal particles forming the conductive layer aggregate. Therefore, thesurface of the conductive layer is rough and has many gaps in astructure. Thus, it is difficult for the EL layer 833 to completelycover the conductive layer; accordingly, the upper electrode and theconductive layer are electrically connected to each other easily, whichis preferable.

The specific example 5 describes the light-emitting panel which can bemanufactured by forming the insulating layer 813, the light-emittingelement 830, and the like over a formation substrate with high heatresistance, separating the formation substrate, and transferring theinsulating layer 813, the light-emitting element 830, and the like tothe substrate 801 with the adhesive layer 811. The insulating layer 813and the like with sufficiently low water permeability are formed overthe formation substrate with high heat resistance at high temperaturesand then are transferred to the substrate 801, whereby a highly reliablelight-emitting panel can be manufactured. Thus, according to oneembodiment of the present invention, a lightweight or thin and highlyreliable light-emitting panel can be realized.

EXAMPLES OF MATERIALS

Next, materials and the like that can be used for a light-emitting panelwill be described. Note that description on the components alreadydescribed in this specification may be omitted in some cases.

For each of the substrates, a material such as glass, quartz, an organicresin, a metal, or an alloy can be used. For the substrate on the sidefrom which light from the light-emitting element is extracted, amaterial which transmits that light is used.

It is particularly preferable to use a flexible substrate. For example,an organic resin or glass, a metal, or an alloy that is thin enough tohave flexibility can be used.

An organic resin, which has a specific gravity smaller than that ofglass, is preferably used for the flexible substrate, in which case thelight-emitting panel can be more lightweight than in the case whereglass is used.

For the substrates, a material with high toughness is preferably used.Accordingly, a light-emitting panel with high impact resistance that isrobust can be realized. For example, when an organic resin substrate, athin metal substrate, or a thin alloy substrate is used, thelight-emitting panel which is lighter and more robust than in the casewhere a glass substrate is used can be realized.

A metal material and an alloy material, which have high thermalconductivity, are preferred because they can easily conduct heat to thewhole substrate and accordingly can reduce a local temperature rise inthe light-emitting panel. The thickness of a substrate using a metalmaterial or an alloy material is preferably greater than or equal to 10μm and less than or equal to 200 μm, further preferably greater than orequal to 20 μm and less than or equal to 50 μm.

There is no particular limitation on a material of the metal substrateor the alloy substrate, but it is preferable to use, for example,aluminum, copper, nickel, or a metal alloy such as an aluminum alloy orstainless steel.

Furthermore, when a material with high thermal emissivity is used forthe substrate, a surface temperature rise of the light-emitting panelcan be reduced, leading to reduction of breakage or a decrease inreliability of the light-emitting panel. For example, the substrate mayhave a stacked-layer structure of a metal substrate and a layer withhigh thermal emissivity (e.g., a metal oxide or a ceramic material canbe used).

Examples of such a material having flexibility and a light-transmittingproperty include polyester resins such as polyethylene terephthalate(PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, apolyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC)resin, a polyethersulfone (PES) resin, a polyamide resin, a cycloolefinresin, a polystyrene resin, a polyamide imide resin, and a polyvinylchloride resin. In particular, a material whose coefficient of thermalexpansion is low is preferably used, and for example, a polyamide imideresin, a polyimide resin, or PET can be suitably used. A substrate inwhich a fibrous body is impregnated with a resin (also referred to asprepreg) or a substrate whose coefficient of thermal expansion isreduced by mixing an organic resin with an inorganic filler can also beused.

The flexible substrate may have a stacked-layer structure in which ahard coat layer (such as a silicon nitride layer) by which a devicesurface is protected from damage or the like, a layer (such as an aramidresin layer) that can disperse pressure, or the like is stacked over alayer of any of the above-mentioned materials.

For the flexible substrate, a plurality of layers may be stacked andused. With a structure including a glass layer, a barrier propertyagainst water and oxygen can be improved and thus a reliablelight-emitting panel can be provided.

For example, a flexible substrate in which a glass layer, an adhesivelayer, and an organic resin layer are stacked from the side closer to alight-emitting element can be used. The thickness of the glass layer isgreater than or equal to 20 μm and less than or equal to 200 μm,preferably greater than or equal to 25 μm and less than or equal to 100μm. With such a thickness, the glass layer can realize both an excellentbarrier property against water and oxygen and a high flexibility. Thethickness of the organic resin layer is greater than or equal to 10 μmand less than or equal to 200 μm, preferably greater than or equal to 20μm and less than or equal to 50 μm. By providing such an organic resinlayer outside the glass layer, a crack or a break in the glass layer canbe reduced and mechanical strength can be improved. With the substratethat includes such a composite material of a glass material and anorganic resin, a highly reliable and flexible light-emitting panel canbe provided.

As the adhesive layer or the sealing layer, a variety of curableadhesives such as a reactive curable adhesive, a thermosetting adhesive,an anaerobic adhesive, and a photo curable adhesive such as anultraviolet curable adhesive can be used. Examples of these adhesivesinclude an epoxy resin, an acrylic resin, a silicone resin, a phenolresin, a polyimide resin, an imide resin, a PVC (polyvinyl chloride)resin, a PVB (polyvinyl butyral) resin, and an EVA (ethylene vinylacetate) resin. A material with low moisture permeability, such as anepoxy resin, is particularly preferable. Alternatively, atwo-component-mixture-type resin may be used. Alternatively, an adhesivesheet or the like may be used.

In addition, the resin may include a drying agent. For example, asubstance that adsorbs moisture by chemical adsorption, such as an oxideof an alkaline earth metal (e.g., calcium oxide or barium oxide), can beused. Alternatively, a substance that adsorbs moisture by physicaladsorption, such as zeolite or silica gel, may be used. The drying agentis preferably included because it can reduce the entry of an impuritysuch as moisture into a functional element, thereby improving thereliability of the light-emitting panel.

In addition, by mixing a filler with a high refractive index orlight-scattering member into the resin, the efficiency of lightextraction from the light-emitting element can be improved. For example,titanium oxide, barium oxide, zeolite, zirconium, or the like can beused.

There is no particular limitation on the structure of the transistors ofthe light-emitting panel. For example, a staggered transistor or aninverted staggered transistor may be used. Furthermore, the structure ofthe transistor may be either top-gate or bottom-gate. There is noparticular limitation on a semiconductor material used for thetransistors; examples include silicon and germanium. Alternatively, anoxide semiconductor containing at least one of indium, gallium, andzinc, such as an In—Ga—Zn-based metal oxide, may be used.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. It is preferable that a semiconductorhaving crystallinity be used, in which case deterioration of thetransistor characteristics can be reduced.

Here, an oxide semiconductor is preferably used for semiconductordevices such as transistors used for pixels, driver circuits, touchsensors described later, or the like. It is particularly preferable touse an oxide semiconductor having a wider band gap than silicon. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used because off-state current of thetransistor can be reduced.

For example, the oxide semiconductor preferably contains at least atleast indium (In) or zinc (Zn). Further preferably, it contains an oxiderepresented by an In—M—Zn-based oxide (M is a metal such as Al, Ti, Ga,Ge, Y, Zr, Sn, La, Ce, or Hf).

As the semiconductor layer, it is particularly preferable to use anoxide semiconductor film including a plurality of crystal parts whosec-axes are aligned perpendicular to a surface on which the semiconductorlayer is formed or the top surface of the semiconductor layer and inwhich the adjacent crystal parts have no grain boundary.

There is no grain boundary in such an oxide semiconductor; therefore,generation of a crack in an oxide semiconductor film which is caused bystress when a display panel is curved is reduced. Therefore, such anoxide semiconductor can be preferably used for a display panel which hasflexibility and is used in a bent state, or the like.

The use of such materials for the semiconductor layer makes it possibleto realize a highly reliable transistor in which a change in theelectrical characteristics is reduced.

In addition, charge accumulated in a capacitor through a transistor canbe held for a long time because of the low off-state current of thetransistor. When such a transistor is used for a pixel, a driver circuitcan be stopped while a gray scale of an image displayed in each displayregion is maintained. As a result, an electronic device with anextremely low power consumption can be realized.

For stable characteristics of the transistor or the like, a base film ispreferably provided. The base film can be formed with an inorganicinsulating film such as a silicon oxide film, a silicon nitride film, asilicon oxynitride film, or a silicon nitride oxide film to have asingle-layer structure or a stacked-layer structure. The base film canbe formed using a sputtering method, a CVD (Chemical Vapor Deposition)method (e.g., a plasma CVD method, a thermal CVD method, or an MOCVD(Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, acoating method, a printing method, or the like. Note that the base filmis not necessarily provided when not needed. In each of the abovestructure examples, the insulating layer 813 can serve as a base film ofthe transistor.

As the light-emitting element, an element capable of self-emission canbe used, and an element whose luminance is controlled by current orvoltage is included in its category. For example, a light-emitting diode(LED), an organic EL element, an inorganic EL element, or the like canbe used.

The light-emitting element may be top-emission, bottom-emission, ordual-emission. A conductive film that transmits visible light is used asthe electrode on the side from which light is extracted. In addition, aconductive film that reflects visible light is preferably used as theelectrode on the side from which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO: Indium Tin Oxide),indium zinc oxide, zinc oxide, or zinc oxide to which gallium is added.Alternatively, a metal material such as gold, silver, platinum,magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, or titanium; an alloy containing any of these metalmaterials; or a nitride of any of these metal materials (e.g., titaniumnitride) can be used when formed thin so as to have a light-transmittingproperty. Alternatively, a stacked film of any of the above materialscan be used as the conductive layer. For example, a stacked film of ITOand an alloy of silver and magnesium is preferably used, in which caseconductivity can be increased. Further alternatively, graphene or thelike may be used.

For the conductive film that reflects visible light, for example, ametal material such as aluminum, gold, platinum, silver, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or analloy containing any of these metal materials can be used. In addition,lanthanum, neodymium, germanium, or the like may be added to the metalmaterial or the alloy. Furthermore, an alloy containing aluminum (analuminum alloy) such as an alloy of aluminum and titanium, an alloy ofaluminum and nickel, or an alloy of aluminum and neodymium; or an alloycontaining silver such as an alloy of silver and copper, an alloy ofsilver, palladium, and copper, or an alloy of silver and magnesium canbe used. An alloy containing silver and copper is preferable because ofits high heat resistance. Moreover, a metal film or a metal oxide filmis stacked on an aluminum alloy film, whereby oxidation of the aluminumalloy film can be reduced. Examples of a material for the metal film orthe metal oxide film include titanium and titanium oxide. Alternatively,the conductive film that transmits visible light and a film containingany of the above metal materials may be stacked. For example, a stackedfilm of silver and ITO or a stacked film of an alloy of silver andmagnesium and ITO can be used.

The electrodes may be formed separately using an evaporation method or asputtering method. Alternatively, they can be formed using a dischargingmethod such as an ink-jet method, a printing method such as a screenprinting method, or a plating method.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the lower electrode 831 and the upperelectrode 835, holes are injected to the EL layer 833 from the anodeside and electrons are injected from the cathode side. The injectedelectrons and holes are recombined in the EL layer 833 and alight-emitting substance contained in the EL layer 833 emits light.

The EL layer 833 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 833 may further include alayer containing a substance with a high hole-injection property, asubstance with a high hole-transport property, a hole-blocking material,a substance with a high electron-transport property, a substance with ahigh electron-injection property, a substance with a bipolar property (asubstance with a high electron-transport property and hole-transportproperty), or the like.

For the EL layer 833, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may also becontained. Each of the layers included in the EL layer 833 can be formedby a method such as an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an ink jetmethod, a coating method, or the like.

The light-emitting element is preferably provided between a pair ofinsulating films with low water permeability. Thus, the entry of animpurity such as water into the light-emitting element can be reduced,leading to suppression of a decrease in the reliability of thelight-emitting device.

Examples of an insulating film with low water permeability include afilm containing nitrogen and silicon such as a silicon nitride film or asilicon nitride oxide film, a film containing nitrogen and aluminum suchas an aluminum nitride film, and the like. Alternatively, a siliconoxide film, a silicon oxynitride film, an aluminum oxide film, or thelike can be used.

For example, the water vapor permeation amount of the insulating filmwith low water permeability is lower than or equal to 1×10⁻⁵[g/(m²·day)], preferably lower than or equal to 1×10⁻⁶ [g/(m²·day)],further preferably lower than or equal to 1×10⁻⁷ [g/(m²·day)], stillfurther preferably lower than or equal to 1×10⁻⁸ [g/(m²·day)].

An insulating film with low water permeability is preferably used forthe insulating layer 813 and the insulating layer 843.

As the insulating layer 815, for example, an inorganic insulating filmsuch as a silicon oxide film, a silicon oxynitride film, or an aluminumoxide film can be used. For example, as each of the insulating layer817, the insulating layer 817 a, and the insulating layer 817 b, anorganic material such as polyimide, acrylic, polyamide, polyimide amide,or a benzocyclobutene-based resin can be used. Alternatively, alow-dielectric constant material (a low-k material) or the like can beused. Furthermore, each of the insulating layers may be formed bystacking a plurality of insulating films.

The insulating layer 821 is formed using an organic insulating materialor an inorganic insulating material. As the resin, for example, apolyimide resin, a polyamide resin, an acrylic resin, a siloxane resin,an epoxy resin, or a phenol resin can be used. It is particularlypreferable that the insulating layer 821 be formed using aphotosensitive resin material so that a sidewall thereof has an inclinedsurface with continuous curvature.

There is no particular limitation on the method for forming theinsulating layer 821; a photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an ink-jetmethod), a printing method (e.g., screen printing or off-set printing),or the like may be used.

The spacer 827 can be formed using an inorganic insulating material, anorganic insulating material, a metal material, or the like. As theinorganic insulating material and the organic insulating material, forexample, a variety of materials that can be used for the insulatinglayer can be used. As the metal material, titanium, aluminum, or thelike can be used. With a structure in which the spacer 827 containing aconductive material and the upper electrode 835 are electricallyconnected to each other, a potential drop due to the resistance of theupper electrode 835 can be reduced. The spacer 827 may also have eithera tapered shape or an inverse tapered shape.

A conductive layer used in the light-emitting panel, which functions asan electrode or a wiring of the transistor, an auxiliary electrode ofthe light-emitting element, or the like, can be formed to have asingle-layer structure or a stacked-layer structure using a metalmaterial such as molybdenum, titanium, chromium, tantalum, tungsten,aluminum, copper, neodymium, or scandium, or an alloy materialcontaining these elements, for example. Alternatively, the conductivelayer may be formed using a conductive metal oxide. As the conductivemetal oxide, indium oxide (e.g., In₂O₃), tin oxide (e.g., SnO₂), zincoxide (ZnO), ITO, indium zinc oxide (e.g., In₂O₃—ZnO), or any of thesemetal oxide materials in which silicon oxide is contained can be used.

The coloring layer is a colored layer that transmits light in a specificwavelength range. For example, a red (R) color filter for transmittinglight in a red wavelength range, a green (G) color filter fortransmitting light in a green wavelength range, a blue (B) color filterfor transmitting light in a blue wavelength range, or the like can beused. Each coloring layer is formed in a desired position with any ofvarious materials by a printing method, an ink-jet method, an etchingmethod using a photolithography method, or the like.

The light-blocking layer is provided between the adjacent coloringlayers. The light-blocking layer blocks light from an adjacentlight-emitting element to reduce color mixture between adjacentlight-emitting elements. Here, the coloring layer is provided such thatits end portion overlaps with the light-blocking layer, whereby lightleakage can be reduced. As the light-blocking layer, a material thatblocks light from the light-emitting element can be used; for example, ablack matrix may be formed using a resin material containing a metalmaterial, pigment, or dye. Note that it is preferable to provide thelight-blocking layer in a region other than the light-emitting portion,such as a driver circuit portion, in which case undesired leakage ofguided light or the like can be reduced.

Furthermore, an overcoat covering the coloring layer and thelight-blocking layer may be provided. With the overcoat, impurities andthe like contained in the coloring layer can be prevented from beingdiffused into the light-emitting element. The overcoat is formed with amaterial that transmits light emitted from the light-emitting element;for example, an inorganic insulating film such as a silicon nitride filmor a silicon oxide film, an organic insulating film such as an acrylicfilm or a polyimide film can be used, and a stacked-layer structure ofan organic insulating film and an inorganic insulating film may be used.

In addition, in the case where a material of the sealing layer isapplied onto the coloring layer and the light-blocking layer, a materialthat has high wettability with respect to the material of the sealinglayer is preferably used as the material of the overcoat. For example,an oxide conductive film such as an ITO film or a metal film such as anAg film that is thin enough to have a light-transmitting property ispreferably used as the overcoat.

For the connector, it is possible to use a paste-like or sheet-likematerial which is obtained by mixing metal particles into athermosetting resin and for which anisotropic electric conductivity isprovided by thermocompression bonding. As the metal particles, particlesin which two or more kinds of metals are layered, for example, nickelparticles coated with gold are preferably used.

MANUFACTURING METHOD EXAMPLE

Next, a method for manufacturing a light-emitting panel is exemplifiedwith reference to FIGS. 13A to 13C and FIGS. 14A to 14C. Here,description is made using the light-emitting panel having the structurein the specific example 1 (FIG. 11C) as an example.

First, a separation layer 203 is formed over a formation substrate 201,and the insulating layer 813 is formed over the separation layer 203.Next, the plurality of transistors, the conductive layer 857, theinsulating layer 815, the insulating layer 817, the plurality oflight-emitting elements, and the insulating layer 821 are formed overthe insulating layer 813. Note that an opening is formed in theinsulating layer 821, the insulating layer 817, and the insulating layer815 to expose the conductive layer 857 (FIG. 13A).

In addition, a separation layer 207 is formed over a formation substrate205, and the insulating layer 843 is formed over the separation layer207. Next, the light-blocking layer 847, the coloring layer 845, and theovercoat 849 are formed over the insulating layer 843 (FIG. 13B).

As each of the formation substrate 201 and the formation substrate 205,a glass substrate, a quartz substrate, a sapphire substrate, a ceramicsubstrate, a metal substrate, or the like can be used.

In addition, for the glass substrate, for example, a glass material suchas aluminosilicate glass, aluminoborosilicate glass, or bariumborosilicate glass can be used. In the case where the temperature of thelater heat treatment is high, the one having a strain point of 730° C.or higher is preferably used. Note that by containing a large amount ofbarium oxide (BaO), glass which is heat-resistant and more practical canbe obtained. Alternatively, crystallized glass or the like may be used.

In the case where a glass substrate is used as the formation substrate,an insulating film such as a silicon oxide film, a silicon oxynitridefilm, a silicon nitride film, or a silicon nitride oxide film ispreferably formed between the formation substrate and the separationlayer, in which case contamination from the glass substrate can beprevented.

Each of the separation layer 203 and the separation layer 207 is asingle layer or a stacked layer containing an element selected fromtungsten, molybdenum, titanium, tantalum, niobium, nickel, cobalt,zirconium, zinc, ruthenium, rhodium, palladium, osmium, iridium, andsilicon; an alloy material containing the element; or a compoundmaterial containing the element. A crystal structure of a layercontaining silicon may be amorphous, microcrystal, or polycrystal.

The separation layer can be formed by a sputtering method, a plasma CVDmethod, a coating method, a printing method, or the like. Note that acoating method includes a spin coating method, a droplet dischargingmethod, and a dispensing method.

In the case where the separation layer has a single-layer structure, atungsten layer, a molybdenum layer, or a layer containing a mixture oftungsten and molybdenum is preferably formed. Alternatively, a layercontaining an oxide or an oxynitride of tungsten, a layer containing anoxide or an oxynitride of molybdenum, or a layer containing an oxide oran oxynitride of a mixture of tungsten and molybdenum may be formed.Note that a mixture of tungsten and molybdenum corresponds to an alloyof tungsten and molybdenum, for example.

In the case where the separation layer is formed to have a stacked-layerstructure including a layer containing tungsten and a layer containingan oxide of tungsten, the layer containing an oxide of tungsten may beutilized which is formed at the interface between a tungsten layer andan insulating film by forming the layer containing tungsten first andforming an insulating film formed of an oxide thereover. Alternatively,the layer containing an oxide of tungsten may be formed by performingthermal oxidation treatment, oxygen plasma treatment, nitrous oxide(N₂O) plasma treatment, treatment with a highly oxidizing solution suchas ozone water, or the like on the surface of the layer containingtungsten. In addition, plasma treatment or heat treatment may beperformed in an atmosphere of oxygen, nitrogen, or nitrous oxide alone,or a mixed gas of the gas and another gas. Surface condition of theseparation layer is changed by the plasma treatment or heat treatment,whereby adhesion between the separation layer and the insulating filmformed later can be controlled.

Each of the insulating layers can be formed using a sputtering method, aplasma CVD method, a coating method, a printing method, or the like, andcan be a dense film with very low water permeability when formed at adeposition temperature higher than or equal to 250° C. and lower than orequal to 400° C. by a plasma CVD method, for example.

Then, a material for the sealing layer 823 is applied to a surface ofthe formation substrate 205 over which the coloring layer 845 and thelike are provided or a surface of the formation substrate 201 over whichthe light-emitting element 230 and the like are provided, and theformation substrate 201 and the formation substrate 205 are attached sothat these surfaces face each other with the sealing layer 823 providedtherebetween (FIG. 13C).

Next, the formation substrate 201 is separated, and the exposedinsulating layer 813 and the substrate 801 are attached to each otherwith the adhesive layer 811. Furthermore, the formation substrate 205 isseparated, and the exposed insulating layer 843 and the substrate 803are attached to each other with the adhesive layer 841. Although thesubstrate 803 does not overlap with the conductive layer 857 in FIG.14A, the conductive layer 857 and the substrate 803 may overlap witheach other.

Note that a variety of methods can be used as appropriate for theseparation process. For example, in the case where a layer including ametal oxide film is formed as the separation layer on the side incontact with the layer to be separated, the metal oxide film isembrittled by crystallization, whereby the layer to be separated can beseparated from the formation substrate. Alternatively, in the case wherean amorphous silicon film containing hydrogen is formed as theseparation layer between a formation substrate having high heatresistance and a layer to be separated, the amorphous silicon film isremoved by laser light irradiation or etching, whereby the layer to beseparated can be separated from the formation substrate. Alternatively,after a layer including a metal oxide film is formed as the separationlayer on the side in contact with the layer to be separated, the metaloxide film is embrittled by crystallization, and part of the separationlayer is removed by etching using a solution or a fluoride gas such asNF₃, BrF₃, or ClF₃, the separation can be performed at the embrittledmetal oxide film. Further alternatively, a method may be employed inwhich a film containing nitrogen, oxygen, hydrogen, or the like (e.g.,an amorphous silicon film containing hydrogen, an alloy film containinghydrogen, or an alloy film containing oxygen) is used as the separationlayer, and the separation layer is irradiated with laser light torelease the nitrogen, oxygen, or hydrogen contained in the separationlayer as gas, thereby promoting separation between the layer to beseparated and the substrate. Still further alternatively, it is possibleto use a method or the like in which the formation substrate where thelayer to be separated is formed is removed mechanically or removed byetching using a solution or a fluoride gas such as NF₃, BrF₃, or ClF₃,or the like. In this case, the separation layer is not necessarilyprovided.

In addition, when a plurality of the above-described separation methodsare combined, the separation process can be performed easily. In otherwords, separation can be performed with physical force (by a machine orthe like) after performing laser light irradiation, etching on theseparation layer with a gas, a solution, or the like, or mechanicalremoval with a sharp knife, scalpel or the like so that the separationlayer and the layer to be separated are brought into an easily separablestate.

Alternatively, the layer to be separated may be separated from theformation substrate by soaking the interface between the separationlayer and the layer to be separated with a liquid. Furthermore, theseparation may be performed while a liquid such as water is being pouredat the time of separation.

As another separation method, in the case where the separation layer isformed using tungsten, it is preferable that the separation be performedwhile etching the separation layer using a mixed solution of ammoniumwater and a hydrogen peroxide solution.

Note that the separation layer is not necessarily provided in the casewhere separation at an interface between the formation substrate and thelayer to be separated is possible. For example, glass is used as theformation substrate, an organic resin such as polyimide, polyester,polyolefin, polyamide, polycarbonate, or acrylic is formed in contactwith the glass, and an insulating film, a transistor, and the like areformed over the organic resin. In this case, heating the organic resinenables the separation at the interface between the formation substrateand the organic resin. Alternatively, separation at the interfacebetween a metal layer and the organic resin may be performed byproviding the metal layer between the formation substrate and theorganic resin and heating the metal layer by making current to flow inthe metal layer.

Lastly, an opening is formed in the insulating layer 843 and the sealinglayer 823 to expose the conductive layer 857 (FIG. 14B). Note that inthe case of the structure where the substrate 803 overlaps with theconductive layer 857, the opening is formed also in the substrate 803and the adhesive layer 841 so that the conductive layer 857 is exposed(FIG. 14C). There is no particular limitation on the method for formingthe opening. For example, a laser ablation method, an etching method, anion beam sputtering method, or the like may be used. Alternatively, acut may be made in a film over the conductive layer 857 with a sharpknife or the like and part of the film may be separated by physicalforce.

In the above-described manner, the light-emitting panel can bemanufactured.

At least part of this embodiment can be implemented as appropriate incombination with any of the other embodiments described in thisspecification.

Embodiment 3

In this embodiment, structures of a foldable touch panel that isapplicable to a display panel of the electronic device of one embodimentof the present invention will be described with reference to FIGS. 15Ato 15C, FIGS. 16A and 16B, FIGS. 17A to 17c, and FIGS. 18A to 18C. Notethat for a material of each layer, Embodiment 2 can be referred to.

STRUCTURE EXAMPLE 1

FIG. 15A is a top view of the touch panel. FIG. 15B is a cross-sectionalview along dashed-dotted line A-B and dashed-dotted line C-D in FIG.15A. FIG. 15C is a cross-sectional view along dashed-dotted line E-F inFIG. 15A.

As illustrated in FIG. 15A, a touch panel 390 includes a display portion301.

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308. The imaging pixels 308 can sense atouch of a finger or the like on the display portion 301. Thus, a touchsensor can be formed using the imaging pixels 308.

The pixels 302 include a plurality of sub-pixels (e.g., a sub-pixel302R). In the sub-pixels, light-emitting elements and pixel circuitsthat can supply electric power for driving the light-emitting elementsare provided.

The pixel circuits are electrically connected to wirings through whichselection signals can be supplied and wirings through which imagesignals can be supplied.

Furthermore, the touch panel 390 is provided with a scan line drivercircuit 303 g(1) that can supply selection signals to the pixels 302 andan image signal line driver circuit 303 s(1) that can supply imagesignals to the pixels 302.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits that drive the photoelectric conversion elements.

The imaging pixel circuits are electrically connected to wirings throughwhich control signals can be supplied and wirings through which powersupply potentials can be supplied.

Examples of the control signals include a signal capable of selecting animaging pixel circuit from which a recorded imaging signal is read, asignal capable of initializing an imaging pixel circuit, and a signalcapable of determining the time it takes for an imaging pixel circuit tosense light.

The touch panel 390 is provided with an imaging pixel driver circuit 303g(2) that can supply control signals to the imaging pixels 308 and animaging signal line driver circuit 303 s(2) that reads out imagingsignals.

As illustrated in FIG. 15B, the touch panel 390 includes a substrate 510and a substrate 570 that faces the substrate 510.

A flexible material can be favorably used for the substrate 510 and thesubstrate 570.

A material with which passage of impurities is reduced can be favorablyused for the substrate 510 and the substrate 570. For example, amaterial with a water vapor permeability of lower than or equal to 10⁻⁵g/(m²·day), preferably lower than or equal to 10⁻⁶ g/(m²·day) can befavorably used.

For the substrate 510 and the substrate 570, materials whosecoefficients of linear expansion are substantially equal can befavorably used. For example, materials whose coefficients of linearexpansion are lower than or equal to 1×10⁻³/K, preferably lower than orequal to 5×10⁻⁵/K, and further preferably lower than or equal to1×10⁻⁵/K can be favorably used.

The substrate 510 is a stacked body including a flexible substrate 510b, an insulating layer 510 a that prevents diffusion of impurities intothe light-emitting elements, and an adhesive layer 510 c that attachesthe flexible substrate 510 b and the insulating layer 510 a to eachother.

The substrate 570 is a stacked body including a flexible substrate 570b, an insulating layer 570 a that prevents diffusion of impurities intothe light-emitting elements, and an adhesive layer 570 c that attachesthe flexible substrate 570 b and the insulating layer 570 a to eachother.

For example, a material that includes polyester, polyolefin, polyamide(e.g., nylon, aramid), polyimide, polycarbonate, or a resin having anacrylic, urethane, epoxy, or siloxane bond can be used for the adhesivelayer.

A sealing layer 560 attaches the substrate 570 and the substrate 510 toeach other. The sealing layer 560 has a refractive index higher thanthat of air. In addition, in the case where light is extracted throughthe sealing layer 560, the sealing layer 560 also serves as a layer(hereinafter, also referred to as an optical bonding layer) thatoptically bonds two members (here, the substrate 570 and the substrate510) between which the sealing layer 560 is sandwiched. The pixelcircuits and the light-emitting elements (e.g., a first light-emittingelement 350R) are provided between the substrate 510 and the substrate570.

The pixel 302 includes the sub-pixel 302R, a sub-pixel 302G, and asub-pixel 302B (FIG. 15C). In addition, the sub-pixel 302R includes alight-emitting module 380R, the sub-pixel 302G includes a light-emittingmodule 380G, and the sub-pixel 302B includes a light-emitting module380B.

For example, the sub-pixel 302R includes the light-emitting element 350Rand the pixel circuit that can supply electric power to thelight-emitting element 350R and includes a transistor 302 t (FIG. 15B).Furthermore, the light-emitting module 380R includes the light-emittingelement 350R and an optical element (e.g., a coloring layer 367R).

The light-emitting element 350R includes a lower electrode 351R, anupper electrode 352, and an EL layer 353 between the lower electrode351R and the upper electrode 352 (FIG. 15C).

The EL layer 353 includes a first EL layer 353 a, a second EL layer 353b, and an intermediate layer 354 between the first EL layer 353 a andthe second EL layer 353 b.

The light-emitting module 380R includes the coloring layer 367R on thesubstrate 570. The coloring layer transmits light of a particularwavelength, and for example, the one that selectively transmits light ofred, green, blue, or the like can be used. Alternatively, a region thattransmits light emitted from the light-emitting element as it is may beprovided.

The light-emitting module 380R, for example, includes the sealing layer360 that is in contact with the light-emitting element 350R and thecoloring layer 367R.

The coloring layer 367R is positioned to overlap with the light-emittingelement 350R. Accordingly, part of light emitted from the light-emittingelement 350R passes through the sealing layer 360 that also serves as anoptical bonding layer and through the coloring layer 367R and is emittedto the outside of the light-emitting module 380R as indicated by arrowsin drawings.

The touch panel 390 includes a light-blocking layer 367BM on thesubstrate 570. The light-blocking layer 367BM is provided so as tosurround the coloring layer (e.g., the coloring layer 367R).

The touch panel 390 includes an anti-reflective layer 367 p positionedto overlap with the display portion 301. As the anti-reflective layer367 p, a circular polarizing plate can be used, for example.

The touch panel 390 includes an insulating layer 321. The insulatinglayer 321 covers the transistor 302 t. Note that the insulating layer321 can be used as a layer for planarizing unevenness caused by thepixel circuits. In addition, an insulating layer on which a layer thatcan reduce the diffusion of impurities into the transistor 302 t and thelike is stacked can be used as the insulating layer 321.

The touch panel 390 includes the light-emitting elements (e.g., thelight-emitting element 350R) over the insulating layer 321.

The touch panel 390 includes, over the insulating layer 321, a partition328 that overlaps with an end portion of the lower electrode 351R. Inaddition, a spacer 329 that controls the distance between the substrate510 and the substrate 570 is provided over the partition 328.

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit and the pixelcircuits can be formed in the same process over the same substrate. Asillustrated in FIG. 15B, the transistor 303 t may include a second gate304 over the insulating layer 321. The second gate 304 may beelectrically connected to a gate of the transistor 303 t. Alternatively,different potentials may be supplied thereto. In addition, the secondgate 304 may be provided in a transistor 308 t, the transistor 302 t, orthe like if necessary.

The imaging pixel 308 includes a photoelectric conversion element 308 pand an imaging pixel circuit for sensing light with which thephotoelectric conversion element 308 p is irradiated. In addition, theimaging pixel circuit includes the transistor 308 t.

For example, a pin photodiode can be used as the photoelectricconversion element 308 p.

The touch panel 390 includes a wiring 311 through which a signal can besupplied. The wiring 311 is provided with a terminal 319. Note that anFPC 309(1) through which signals such as an image signal and asynchronization signal can be supplied is electrically connected to theterminal 319. Note that a printed wiring board (PWB) may be attached tothe FPC 309(1).

Transistors formed in the same process can be used as transistors suchas the transistor 302 t, the transistor 303 t, and the transistor 308 t.Embodiment 2 can be referred to for the structures of the transistors.

As a material that can be used for a gate, a source, and a drain of atransistor, and a variety of wirings and electrodes included in a touchpanel, a single-layer structure or a stacked-layer structure using ametal such as aluminum, titanium, chromium, nickel, copper, yttrium,zirconium, molybdenum, silver, tantalum, or tungsten, or an alloycontaining the same as its main component is used. Examples include asingle-layer structure of an aluminum film containing silicon, atwo-layer structure in which an aluminum film is stacked over a titaniumfilm, a two-layer structure in which an aluminum film is stacked over atungsten film, a two-layer structure in which a copper film is stackedover a copper-magnesium-aluminum alloy film, a two-layer structure inwhich a copper film is stacked over a titanium film, a two-layerstructure in which a copper film is stacked over a tungsten film, athree-layer structure in which a titanium film or a titanium nitridefilm, an aluminum film or a copper film stacked over the titanium filmor the titanium nitride film, and a titanium film or a titanium nitridefilm thereover are formed, a three-layer structure in which a molybdenumfilm or a molybdenum nitride film, an aluminum film or a copper filmstacked over the molybdenum film or the molybdenum nitride film, and amolybdenum film or a molybdenum nitride film thereover are formed, andthe like. Note that a transparent conductive material containing indiumoxide, tin oxide, or zinc oxide may be used. In addition, coppercontaining manganese is preferable because controllability of a shape byetching is increased.

STRUCTURE EXAMPLE 2

FIGS. 16A and 16B are perspective views of a touch panel 505. Note thatmain components are illustrated for simplicity. FIGS. 17A to 17C arecross-sectional views along dashed-dotted line X1-X2 illustrated in FIG.16A.

The touch panel 505 includes a display portion 501 and a touch sensor595 (FIG. 16B). Furthermore, the touch panel 505 includes the substrate510, the substrate 570, and a substrate 590. Note that the substrate510, the substrate 570, and the substrate 590 each have flexibility.

The display portion 501 includes the substrate 510, a plurality ofpixels over the substrate 510, and a plurality of wirings 511 throughwhich signals can be supplied to the pixels. The plurality of wirings511 are led to a peripheral portion of the substrate 510, and portionsthereof form a terminal 519. The terminal 519 is electrically connectedto an FPC 509(1).

The substrate 590 includes the touch sensor 595 and a plurality ofwirings 598 electrically connected to the touch sensor 595. Theplurality of wirings 598 are led to a peripheral portion of thesubstrate 590, and portions thereof form a terminal. The terminal iselectrically connected to an FPC 509(2). Note that in FIG. 16B,electrodes, wirings, and the like of the touch sensor 595 provided onthe back surface side of the substrate 590 (on the substrate 510 side)are indicated by solid lines for clarity.

As the touch sensor 595, a capacitive touch sensor can be used, forexample. Examples of the capacitive type include a surface capacitivetype and a projected capacitive type.

Examples of the projected capacitive type are a self-capacitive type anda mutual capacitive type, which differ mainly in the driving method. Theuse of the mutual capacitive type is preferable because multiple pointscan be detected simultaneously.

A case of using a projected capacitive touch sensor will be describedbelow with reference to FIG. 16B.

Note that a variety of sensors that can sense the approach or contact ofa sensing target such as a finger can be used.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

The electrodes 592 each have a shape of a plurality of quadranglesarranged in one direction with one corner of a quadrangle connected toone corner of another quadrangle as illustrated in FIGS. 16A and 16B.

The electrodes 591 each have a quadrangular shape and are arranged in adirection intersecting with the direction in which the electrodes 592extend.

A wiring 594 electrically connects two electrodes 591 between which oneelectrode 592 is sandwiched. At this time, a shape where theintersecting area of the electrode 592 and the wiring 594 is as small aspossible is preferable. This allows a reduction in the area of a regionwhere the electrodes are not provided, reducing unevenness intransmittance. As a result, unevenness in luminance of light transmittedthrough the touch sensor 595 can be reduced.

Note that the shapes of the electrodes 591 and the electrodes 592 arenot limited thereto and can be any of a variety of shapes. For example,the plurality of electrodes 591 may be provided so that spacestherebetween are reduced as much as possible, and a plurality ofelectrodes 592 may be provided with an insulating layer providedtherebetween and may be spaced apart from each other to form a regionnot overlapping with the electrodes 591. At this time, between twoadjacent electrodes 592, a dummy electrode that is electricallyinsulated from these is preferably provided, whereby the area of aregion having a different transmittance can be reduced.

The touch sensor 595 includes the substrate 590, the electrodes 591 andthe electrodes 592 provided in a staggered arrangement over thesubstrate 590, an insulating layer 593 covering the electrodes 591 andthe electrodes 592, and the wiring 594 that electrically connects theadjacent electrodes 591 to each other.

An adhesive layer 597 attaches the substrate 590 to the substrate 570 sothat the touch sensor 595 overlaps with the display portion 501.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As the light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded can be used. Note that a film including graphene may be used aswell. The film including graphene can be formed, for example, byreducing a film including graphene oxide formed in the form of a film.As a reducing method, a method with application of heat or the like canbe employed.

The electrodes 591 and the electrodes 592 may be formed by depositing alight-transmitting conductive material over the substrate 590 by asputtering method and then removing an unnecessary portion by any ofvarious patterning techniques such as a photolithography method.

As a material that is used for the insulating layer 593, a resin such asacrylic or epoxy, a resin having a siloxane bond, or an inorganicinsulating material such as silicon oxide, silicon oxynitride, oraluminum oxide can also be used.

Furthermore, openings reaching the electrodes 591 are formed in theinsulating layer 593, and the wiring 594 electrically connects theadjacent electrodes 591. A light-transmitting conductive material can befavorably used for the wiring 594 because the aperture ratio of thetouch panel can be increased. Moreover, a material with higherconductivity than those of the electrodes 591 and the electrodes 592 canbe favorably used for the wiring 594 because electric resistance can bereduced.

One of the electrodes 592 extends in one direction, and a plurality ofelectrodes 592 are provided in the form of stripes.

The wiring 594 is provided so as to intersect with the electrodes 592.

A pair of electrodes 591 are provided with one of the electrodes 592provided therebetween. The wiring 594 electrically connects the pair ofelectrodes 591.

Note that the plurality of electrodes 591 are not necessarily arrangedin the direction orthogonal to one electrode 592 and may be arranged atan angle of less than 90 degrees.

One wiring 598 is electrically connected to any of the electrodes 591and the electrodes 592. Part of the wiring 598 serves as a terminal. Forthe wiring 598, a metal material such as aluminum, gold, platinum,silver, nickel, titanium, tungsten, chromium, molybdenum, iron, cobalt,copper, or palladium or an alloy material containing the metal materialcan be used.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

Furthermore, a connection layer 599 electrically connects the wiring 598and the FPC 509(2) to each other.

As the connection layer 599, any of various anisotropic conductive films(ACF: Anisotropic Conductive Film), anisotropic conductive pastes (ACP:Anisotropic Conductive Paste), and the like can be used.

The adhesive layer 597 has a light-transmitting property. For example, athermosetting resin or an ultraviolet curable resin can be used;specifically, a resin such as acrylic, urethane, epoxy, a resin having asiloxane bond, or the like can be used.

The display portion 501 includes a plurality of pixels arranged in amatrix. The pixel includes a display element and a pixel circuit fordriving the display element.

In this embodiment, a case of using an organic EL element that emitswhite light as a display element will be described; however, the displayelement is not limited thereto.

For example, organic EL elements that emit light of different colors maybe used in sub-pixels so that the light of different colors can beemitted from the respective sub-pixels.

The substrate 510, the substrate 570, and the sealing layer 560 can havestructures similar to those in the structure example 1.

A pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes a light-emitting element 550R and a pixelcircuit including a transistor 502 t that can supply electric power tothe light-emitting element 550R. Furthermore, the light-emitting module580R includes the light-emitting element 550R and an optical element(e.g., a coloring layer 567R).

The light-emitting element 550R includes a lower electrode, an upperelectrode, and an EL layer between the lower electrode and the upperelectrode.

The light-emitting module 580R includes the coloring layer 567R on thelight extraction side.

Furthermore, in the case where the sealing layer 560 is provided on thelight extraction side, the sealing layer 560 is in contact with thelight-emitting element 550R and the coloring layer 567R.

The coloring layer 567R is positioned to overlap with the light-emittingelement 550R. Accordingly, part of light emitted from the light-emittingelement 550R passes through the coloring layer 567R and is emitted tothe outside of the light-emitting module 580R in a direction of an arrowillustrated in the drawing.

The display portion 501 includes a light-blocking layer 567BM in thelight emitting direction. The light-blocking layer 567BM is provided soas to surround the coloring layer (e.g., the coloring layer 567R).

The display portion 501 includes an anti-reflective layer 567 ppositioned to overlap with pixels. As the anti-reflective layer 567 p, acircular polarizing plate can be used, for example.

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness caused by the pixelcircuits. A stacked film including a layer that can reduce the diffusionof impurities can be used as the insulating film 521. This can suppressa decrease in the reliability of the transistor 502 t or the like bydiffusion of impurities.

The display portion 501 includes the light-emitting elements (e.g., thelight-emitting element 550R) over the insulating film 521.

The display portion 501 includes, over the insulating film 521, apartition 528 that overlaps with an end portion of a lower electrode. Inaddition, a spacer that controls the distance between the substrate 510and the substrate 570 is provided over the partition 528.

A scan line driver circuit 503 g(1) includes a transistor 503 t and acapacitor 503 c. Note that the driver circuit and the pixel circuits canbe formed in the same process over the same substrate.

The display portion 501 includes the wirings 511 through which signalscan be supplied. The wirings 511 are provided with the terminal 519.Note that the FPC 509(1) through which signals such as an image signaland a synchronization signal can be supplied is electrically connectedto the terminal 519.

Note that a printed wiring board (PWB) may be attached to the FPC509(1).

The display portion 501 includes wirings such as scan lines, signallines, and power supply lines. The variety of conductive films describedabove can be used as the wirings.

Note that a variety of transistors can be used in the display portion501. A structure in the case of using bottom-gate transistors in thedisplay portion 501 is illustrated in FIGS. 17A and 17B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 17A.

For example, a semiconductor layer containing polycrystalline siliconthat is obtained by crystallization process such as laser annealing canbe used in the transistor 502 t and the transistor 503 t illustrated inFIG. 17B.

In addition, a structure in the case of using top-gate transistors inthe display portion 501 is illustrated in FIG. 17C.

For example, a semiconductor layer including polycrystalline silicon, asingle crystal silicon film that is transferred from a single crystalsilicon substrate, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 17C.

STRUCTURE EXAMPLE 3

FIGS. 18A to 18C are cross-sectional views of a touch panel 505B. Thetouch panel 505B described in this embodiment is different from thetouch panel 505 in the structure example 2 in including the displayportion 501 that displays supplied image data to the side where thetransistors are provided and in being provided with the touch sensor onthe substrate 510 side of the display portion. Different structures willbe described in detail here, and the above description is referred tofor portions that can use similar structures.

The coloring layer 567R is positioned to overlap with the light-emittingelement 550R. In addition, the light-emitting element 550R illustratedin FIG. 18A emits light to the side where the transistor 502 t isprovided. Accordingly, part of light emitted from the light-emittingelement 550R passes through the coloring layer 567R and is emitted tothe outside of the light-emitting module 580R in a direction of an arrowillustrated in the drawing.

The display portion 501 includes the light-blocking layer 567BM in thelight emitting direction. The light-blocking layer 567BM is provided soas to surround the coloring layer (e.g., the coloring layer 567R).

The touch sensor 595 is provided on the substrate 510 side of thedisplay portion 501 (FIG. 18A).

The adhesive layer 597 is provided between the substrate 510 and thesubstrate 590 and attaches the touch sensor 595 and the display portion501 to each other.

Note that a variety of transistors can be used in the display portion501. A structure in the case of using bottom-gate transistors in thedisplay portion 501 is illustrated in FIGS. 18A and 18B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 18A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 18B.

In addition, a structure in the case of using top-gate transistors inthe display portion 501 is illustrated in FIG. 18C.

For example, a semiconductor layer including polycrystalline silicon, atransferred single crystal silicon film, or the like can be used in thetransistor 502 t and the transistor 503 t illustrated in FIG. 18C.

At least part of this embodiment can be implemented as appropriate incombination with any of the other embodiments described in thisspecification.

Embodiment 4

In this embodiment, an example of a driving method of a touch panel thatis applicable to a display panel of the electronic device of oneembodiment of the present invention will be described with reference todrawings.

EXAMPLE OF SENSING METHOD OF SENSOR

FIG. 19A is a block diagram illustrating the structure of a mutualcapacitive touch sensor. FIG. 19A illustrates a pulse voltage outputcircuit 601 and a current detection circuit 602. Note that in FIG. 19A,electrodes 621 to which a pulse voltage is applied and electrodes 622that sense changes in current are denoted by six wirings X1-X6 andY1-Y6, respectively. In addition, FIG. 19A also illustrates a capacitor603 that is formed by an electrode 121 and an electrode 122 overlappingwith each other. Note that the functions of the electrode 121 and theelectrode 122 may be interchanged with each other.

The pulse voltage output circuit 601 is a circuit for sequentiallyapplying a pulse voltage to the wirings X1-X6. By application of a pulsevoltage to the wirings X1-X6, an electric field is generated between theelectrode 121 and the electrode 122 which form the capacitor 603. Byutilizing a change in the mutual capacitance of the capacitor 603 whichis caused when the electric field generated between the electrodes isshielded, for example, the approach or contact of a sensing target canbe detected.

The current detection circuit 602 is a circuit for detecting changes incurrent through the wirings Y1-Y6 that are caused by the change in themutual capacitance in the capacitor 603. No change in current value isdetected in the wirings Y1-Y6 when there is no approach or contact of asensing target, whereas a decrease in current value is detected as achange when mutual capacitance is decreased owing to the approach orcontact of a sensing target to be detected. Note that current detectionmay be performed using an integrator circuit or the like.

Next, FIG. 19B illustrates a timing chart with input and outputwaveforms in the mutual capacitive touch sensor illustrated in FIG. 19A.In FIG. 19B, detection of a sensing target is performed in all the rowsand columns in one frame period. Furthermore, FIG. 19B illustrates twocases: a case where a sensing target is not detected (not touched) and acase where a sensing target is detected (touched). Note that thewaveforms of voltage values corresponding to detected current values areillustrated for the wirings Y1-Y6.

A pulse voltage is sequentially applied to the wirings X1-X6, and thewaveforms of the wirings Y1-Y6 change in accordance with the pulsevoltage. In the case where there is no approach or contact of a sensingtarget, the waveforms of the Y1-Y6 uniformly change in accordance withchanges in the voltages of the wirings X1-X6. Meanwhile, the currentvalue is decreased at the point of approach or contact of a sensingtarget and accordingly the waveform of the corresponding voltage valuealso changes.

By detecting a change in mutual capacitance in this manner, the approachor contact of a sensing target can be sensed.

Although FIG. 19A illustrates a passive-matrix touch sensor in whichonly the capacitor 603 is provided as a touch sensor at the intersectionof wirings, an active-matrix touch sensor including a transistor and acapacitor may also be used. FIG. 20 illustrates an example of a sensorcircuit included in an active-matrix touch sensor.

The sensor circuit includes the capacitor 603, a transistor 611, atransistor 612, and a transistor 613. The transistor 613 has a gatesupplied with a signal G2, has one of a source and a drain supplied witha voltage VRES, and has the other electrically connected to oneelectrode of the capacitor 603 and a gate of the transistor 611. Thetransistor 611 has one of a source and a drain electrically connected toone of a source and a drain of the transistor 612, and has the othersupplied with a voltage VSS. The transistor 612 has a gate supplied witha signal G2, and has the other of the source and the drain electricallyconnected to a wiring ML. The other electrode of the capacitor 603 issupplied with the voltage VSS.

Next, the operation of the sensor circuit will be described. First, apotential for turning on the transistor 613 is applied as the signal G2,and a potential corresponding to the voltage VRES is thus applied to anode n to which the gate of the transistor 611 is connected. Then, apotential for turning off the transistor 613 is applied as the signalG2, and the potential of the node n is thus retained.

Then, mutual capacitance of the capacitor 603 changes owing to theapproach or contact of a sensing target such as a finger, andaccordingly the potential of the node n is changed from VRES.

In a reading operation, a potential for turning on the transistor 612 isapplied as the signal G1. A current flowing through the transistor 611,that is, a current flowing through the wiring ML is changed inaccordance with the potential of the node n. By detecting this current,the approach or contact of a sensing target can be detected.

It is preferable that transistors in which an oxide semiconductor isused for a semiconductor layer where a channel is formed be used as thetransistor 611, the transistor 612, and the transistor 613. Inparticular, by using such a transistor as the transistor 613, thepotential of the node n can be retained for a long time and thefrequency of operation of resupplying VRES to the node n (refreshoperation) can be reduced.

DRIVING METHOD EXAMPLE FOR DISPLAY DEVICE

FIG. 21A is a block diagram illustrating an example of the structure ofa display device. FIG. 21A illustrates a gate driver circuit GD, asource driver circuit SD, and pixels pix. Note that in FIG. 21A, thepixels pix are denoted by (1, 1) to (n, m) which correspond to gatelines x_1 to x_m (m is a natural number) electrically connected to thegate driver circuit GD and source lines y_1 to y_n (n is a naturalnumber) electrically connected to the source driver circuit SD.

Next, FIG. 21B is a timing chart of signals supplied to the gate linesand the source lines in the display device illustrated in FIG. 21A. Theperiods in FIG. 21B show the case where data signals are rewritten everyframe period and the case where data signals are not rewritten. Notethat periods such as a retrace period are not taken into considerationin FIG. 21B.

In the case where data signals are rewritten every frame period, scansignals are sequentially supplied to the gate lines x_1 to x_m. In ahorizontal scanning period 1H, during which the scan signal is at Hlevel, data signals D are supplied to the source lines y_l to y_n in thecolumns.

In the case where data signals are not rewritten every frame period, thescan signals supplied to the gate lines x_1 to x_m are stopped. In thehorizontal scanning period 1H, the data signals supplied to the sourcelines y_1 to y_n in the columns are stopped.

A driving method in which data signals are not rewritten every frameperiod is effective particularly in the case where an oxidesemiconductor is used for a semiconductor layer where a channel isformed as a transistor included in a pixel. A transistor in which anoxide semiconductor is used can have much lower off-state current than atransistor in which a semiconductor such as silicon is used. Thus, datawritten in the previous period can be retained without rewriting datasignals every frame period, and the gray levels of pixels can beretained for 1 second or longer, preferably 5 seconds or longer, forexample.

EXAMPLE OF DRIVING METHOD FOR DISPLAY DEVICE AND TOUCH SENSOR

FIGS. 22A to 22D are diagrams illustrating examples of the operations insuccessive frame periods of the touch sensor described with FIGS. 19Aand 19B and the display device described with FIGS. 21A and 21B that aredriven for 1 sec (one second). Note that FIG. 22A illustrates a casewhere one frame period for the display device is 16.7 ms (framefrequency: 60 Hz), and one frame period for the touch sensor is 16.7 ms(frame frequency: 60 Hz).

In the touch panel of this embodiment, the display device and the touchsensor operate independently of each other, and a touch sensing periodcan be concurrent with a display period. That is why one frame periodsfor the display device and the touch sensor can both be 16.7 ms (framefrequency: 60 Hz) as illustrated in FIG. 22A. The frame frequencies forthe touch sensor and the display device may differ from each other. Forexample, as illustrated in FIG. 22B, one frame period for the displaydevice may be set to 8.3 ms (frame frequency: 120 Hz) and one frameperiod for the touch sensor may be 16.7 ms (frame frequency: 60 Hz).Although not illustrated, the frame frequency for the display device mayalso be 33.3 ms (frame frequency: 30 Hz).

The frame frequency for the display device may be changeable, i.e., theframe frequency in displaying moving images may be increased (e.g., 60Hz or more, or 120 Hz or more), whereas the frame frequency indisplaying still images may be decreased (e.g., 60 Hz or less, 30 Hz orless, or 1 Hz or less). Accordingly, power consumption of the displaydevice can be reduced. The frame frequency for the touch sensor may bechangeable so that the frame frequencies in waiting and in sensing atouch differ from each other.

In addition, the touch panel of this embodiment retains data rewrittenin the previous period without rewriting data signals in the displaydevice, and one frame period for the display device can thus be a periodlonger than 16.7 ms. Thus, as illustrated in FIG. 22C, one frame periodfor the display device can be set to 1 sec (frame frequency: 1 Hz) andone frame period for the touch sensor can be 16.7 ms (frame frequency:60 Hz).

Furthermore, the touch panel of this embodiment can continue to drivethe touch sensor in the case of the driving illustrated in FIG. 22C.Thus, data signals in the display device can be rewritten at the timingat which the approach or contact of a sensing target is sensed by thetouch sensor, as illustrated in FIG. 22D.

If the operation of rewriting data signals in a display device isperformed during a sensing period of a touch sensor, noise caused bydriving the display device might be transmitted to the touch sensor,lowering the sensitivity of the touch sensor. For this reason, drivingis preferably performed such that a rewriting period for data signals ina display device and a sensing period for a touch sensor are differentperiods.

FIG. 23A illustrates an example in which rewriting of data signals in adisplay device and sensing in a touch sensor are performed alternately.In addition, FIG. 23B illustrates an example in which sensing in a touchsensor is performed once every other operation of rewriting data signalsin a display device. Note that without being limited thereto, sensing ina touch sensor may be performed once every three or more rewritingoperations.

In addition, in the case where an oxide semiconductor is used as asemiconductor where a channel is formed in a transistor used in a pixelof a display device, the off-state current can be significantly reducedand the frequency of rewriting data signals can be sufficiently reduced.Specifically, a sufficiently long break period can be provided afterdata signal rewriting and before the next data signal rewriting. Thebreak period can be 0.5 seconds or longer, 1 second or longer, or 5seconds or longer, for example. The upper limit of the break period,which is restricted by the leakage current of a capacitor or a displayelement connected to a transistor, can be, for example, approximately 1minute or shorter, 10 minutes or shorter, 1 hour or shorter, or 1 day orshorter.

FIG. 23C illustrates an example in which rewriting of data signals in adisplay device is performed once every 5 seconds. In FIG. 23C, a breakperiod for stopping the operation of a display device is provided afterdata signal rewriting and before the next data signal rewritingoperation. In the break period, a touch sensor can be driven at a framefrequency of i Hz (i is more than or equal to the frame frequency of adisplay device; here, 0.2 Hz or more). In addition, it is preferablethat sensing in a touch sensor be performed in a break period and not beperformed in a rewriting period of data signals in a display device asillustrated in FIG. 23C, in which case the sensitivity of the touchsensor can be increased. When rewriting of data signals in a displaydevice and sensing in a touch sensor are performed at the same time asillustrated in FIG. 23D, signals for driving can be simplified.

In a break period during which the operation of rewriting data signalsin a display device is not performed, only the supply of signals to adriver circuit may be stopped, and in addition, the supply of a powersupply potential may be stopped for further reducing power consumption.

The touch panel of one embodiment of the present invention has astructure in which a display device and a touch sensor are sandwichedbetween two flexible substrates, for example, and the distance betweenthe display device and the touch sensor can be extremely reduced. Atthis time, noise caused by driving the display device might be easilytransmitted to the touch sensor, lowering the sensitivity of the touchsensor; by employing the driving method exemplified in this embodiment,a touch panel with both reduced thickness and high detection sensitivitycan be realized.

Embodiment 5

In this embodiment, examples of a structure and a driving method of atouch panel that is applicable to a display panel of the electronicdevice of one embodiment of the present invention will be described withreference to drawings.

[Structure of Touch Panel]

FIG. 24 is a block diagram illustrating a structure example of a touchpanel exemplified below. As illustrated in FIG. 24, a touch panel 90includes a display device 900, a control circuit 910, a counter circuit920, and a touch sensor 950.

An image signal (Video), which is digital data, and a synchronizationsignal (SYNC) for controlling rewriting of a screen of the displaydevice 900 are input to the touch panel 90. Examples of thesynchronization signal include a horizontal synchronization signal(Hsync), a vertical synchronization signal (Vsync), and a referenceclock signal (CLK).

The display device 900 includes a display portion 901, a gate driver902, and a source driver 903. The display portion 901 includes aplurality of pixels PIX. The pixels PIX in the same row are connected tothe gate driver 902 through a common gate line L_X, and the pixels PIXin the same column are connected to the source driver 903 through acommon source line L_Y.

A high-level voltage (VH), a low-level voltage (VL), and a high powersupply voltage (VDD) and a low power supply voltage (VSS) which serve aspower supply voltages are supplied to the display device 900. Thehigh-level voltage (VH) is supplied to each pixel PIX in the displayportion 901 through a wiring L_H. The low-level voltage (VL) is suppliedto each pixel PIX in the display portion 901 through a wiring L_L.

The source driver 903 processes an input image signal to generate a datasignal, and outputs the data signal to the source line L_Y. The gatedriver 902 outputs, to the gate line L_X, a scan signal for selectingthe pixel PIX into which a data signal is to be written.

The pixel PIX includes a switching element whose electrical connectionto the source line L_Y is controlled by a scan signal. When theswitching element is turned on, a data signal is written into the pixelPIX through the source line L_Y.

The control circuit 910 is a circuit that controls the whole touch panel90 and includes a circuit that generates control signals for circuitsincluded in the touch panel 90.

The control circuit 910 includes a control signal generation circuitthat generates control signals for the gate driver 902 and the sourcedriver 903 from the synchronization signal (SYNC). Examples of controlsignals for the gate driver 902 include a start pulse (GSP) and a clocksignal (GCLK). Examples of control signals for the source driver 903include a start pulse (SSP) and a clock signal (SCLK). For example, thecontrol circuit 910 generates a plurality of clock signals with the samecycle and shifted phases as the clock signals (GCLK and SCLK).

In addition, the control circuit 910 controls the output of an imagesignal (Video), which is input from the outside of the touch panel 90 tothe source driver 903.

In addition, a sensor signal (S_touch) input from the touch sensor 950is input to the control circuit 910, and an image signal in accordancewith the sensor signal is corrected. The correction of the image signaldepends on the sensor signal; image processing corresponding to touch isperformed.

The source driver 903 includes a digital/analog conversion circuit 904(hereinafter referred to as a D-A conversion circuit 904). The D-Aconversion circuit 904 converts an image signal into an analog signal,thereby generating a data signal.

Note that in the case where an image signal input to the touch panel 90is an analog signal, it is converted into a digital signal in thecontrol circuit 910 and output to the display device 900.

An image signal is image data for each frame. The control circuit 910has a function of performing image processing on the image data andcontrolling output of the image signal to the source driver 903 on thebasis of data obtained by the processing. Therefore, the control circuit910 includes a motion detection portion 911 that performs imageprocessing on the image data to detect motion in accordance with theimage data for each frame. Furthermore, in the case where a sensorsignal is input, the image signal based on the image data is correctedin response to the sensor signal.

When the motion detection portion 911 determines that there is motion,the control circuit 910 continues to output image signals to the sourcedriver 903. Conversely, the control circuit 910 stops the output ofimage signals to the source driver 903 when it is determined that thereis no motion, and restarts the output of image signals when it isdetermined again that there is motion.

The control circuit 910 can control display in the display portion 901by switching between a first mode for displaying images with motion(moving image display) and a second mode for displaying images withoutmotion (still image display), depending on determination by the motiondetection portion 911. The first mode is a mode where when the verticalsynchronization signal (Vsync) is 60 Hz, for example, the framefrequency is set to 60 Hz or higher. The second mode is a mode wherewhen the vertical synchronization signal (Vsync) is 60 Hz, for example,the frame frequency is set to lower than 60 Hz.

The frame frequency set in the second mode is preferably set in advancein accordance with a voltage retaining property of a pixel. For example,in the case where the motion detection portion 911 determines that thereis no motion for a certain period of time and the output of imagesignals to the source driver 903 is stopped, a voltage corresponding tothe gray level of an image signal that is written to the pixel PIX islowered. Therefore, it is preferable to write in a voltage correspondingto the gray level of an image signal for the same image in accordancewith the cycle of the frame frequency (also called refreshing). Astructure may be employed in which the timing of the refreshing (alsoreferred to as a refresh rate) is performed every certain period of timein accordance with, for example, the vertical synchronization signal (asignal obtained by counting the H level of Vsync) in the counter circuit920.

In the case where the refresh rate is set to a frequency of once everysecond with the counter circuit 920, when the frequency of the verticalsynchronization signal (Vsync) is 60 Hz, refresh may be performed inresponse to a count signal (Count) that is obtained by counting the Hlevel of the vertical synchronization signal (Vsync) to 60. In the casewhere the refresh rate is set to a frequency of once every five seconds,when the frequency of the vertical synchronization signal (Vsync) is 60Hz, refresh may be performed in response to a count signal (Count) thatis obtained by counting the H level of the vertical synchronizationsignal (Vsync) to 300. Furthermore, in the case where a sensor signalinput from the touch sensor 950 is input, the counter circuit 920 may beconfigured to forcibly switch from the second mode to the first mode inresponse to the sensor signal.

Note that there is no particular limitation on the image processing fordetecting motion that is performed in the motion detection portion 911.An example of a method for detecting motion is a method to obtaindifference data from image data for two consecutive frames, for example.It can be determined whether there is motion or not from the obtaineddifference data. There is also a method to detect a motion vector or thelike.

The operation and structure described in the above embodiment can beused for the touch sensor 950.

The display device and the touch sensor 950 of this embodiment can beoperated independently of each other; thus, a touch sensing periodconcurrent with a display period can be provided. Even in the structurein which the control circuit 910 switches between the first mode and thesecond mode, the operation of the touch sensor can thus be controlledindependently. By synchronizing the operation of the display device 900with that of the touch sensor 950 and performing the operation ofrewriting data signals in the display device 900 and the sensingoperation in the touch sensor 950 in different periods, the sensitivityof sensing can be increased.

[Structure Example of Pixel]

FIG. 25A is a circuit diagram illustrating a structure example of thepixel PIX. The pixel PIX includes a transistor TR1, a transistor TR2, alight-emitting element EL, and a capacitor CAP.

The transistor TR1 functions as a switching element that controlselectrical connection between the source line L_Y and a gate of thetransistor TR1, and whether it is turned on or off is controlled by ascan signal input to its gate. The transistor TR2 functions as aswitching element for controlling a current supplied to thelight-emitting element EL.

Note that an oxide semiconductor is preferably used for a semiconductorwhere a channel is formed in the transistor TR1 and the transistor TR2.

The light-emitting element EL includes an EL layer containing alight-emitting organic compound sandwiched between two electrodes. Theluminance of light emitted from the light-emitting element depends on acurrent flowing between the two electrodes. A low-level potential isapplied from the wiring L_L to one electrode of the light-emittingelement, and a high-level potential is applied from the wiring L_H tothe other electrode via the transistor TR2.

The capacitor Cap has a function of retaining the potential of the gateof the transistor TR2.

FIG. 25B is an example of the pixel PIX including a liquid crystalelement. The pixel PIX includes a transistor TR, a liquid crystalelement LC, and a capacitor CAP.

The transistor TR is a switching element that controls electricalconnection between one electrode of the liquid crystal element LC andthe source line L_Y, and whether it is turned on or off is controlled bya scan signal input to its gate.

Note that an oxide semiconductor is preferably used as a semiconductorwhere a channel is formed in the transistor TR.

The liquid crystal element LC includes two electrodes and a liquidcrystal. The alignment of the liquid crystal is changed by the action ofan electric field between the two electrodes. One of the two electrodesof the liquid crystal element LC, which is connected to the source lineL_Y through the transistor TR, corresponds to a pixel electrode, and theother, which is connected to a common line L_com to which Vcom isapplied, corresponds to a common electrode.

The capacitor Cap is connected in parallel with the liquid crystalelement LC. In this case, one electrode of the capacitor is connected toa source or a drain of the transistor TR, and the other electrode of thecapacitor is connected to a capacitor line L_cap to which a capacitorline voltage is applied.

Note that although the example where the liquid crystal element LC orthe light-emitting element EL is used as a display element is describedhere, one embodiment of the present invention is not limited thereto.

In this specification and the like, for example, a display element, adisplay device which is a device including a display element, alight-emitting element, and a light-emitting device which is a deviceincluding a light-emitting element can employ a variety of modes or caninclude a variety of elements. The display element, the display device,the light-emitting element, or the light-emitting device includes atleast one of an EL (electroluminescence) element (e.g., an EL elementincluding organic and inorganic materials, an organic EL element, or aninorganic EL element), an LED (e.g., a white LED, a red LED, a greenLED, or a blue LED), a transistor (a transistor that emits lightdepending on current), an electron emitter, a liquid crystal element,electronic ink, an electrophoretic element, a grating light valve (GLV),a plasma display panel (PDP), a display element using MEMS (microelectro mechanical system), a digital micromirror device (DMD), a DMS(digital micro shutter), MIRASOL (registered trademark), aninterferometric modulator (IMOD) element, a MEMS shutter displayelement, an optical-interference-type MEMS display element, anelectrowetting element, a piezoelectric ceramic display, a displayelement including a carbon nanotube, and the like. Other than the above,a display medium whose contrast, luminance, reflectance, transmittance,or the like is changed by electrical or magnetic action may be included.Examples of a display device including an EL element include an ELdisplay. Examples of a display device including an electron emitterinclude a field emission display (FED) and an SED-type flat paneldisplay (SED: Surface-conduction Electron-emitter Display). Examples ofa display device including a liquid crystal element include a liquidcrystal display (a transmissive liquid crystal display, a transflectiveliquid crystal display, a reflective liquid crystal display, adirect-view liquid crystal display, or a projection liquid crystaldisplay). Examples of a display device including electronic ink or anelectrophoretic element include electronic paper. Note that in the caseof realizing a transflective liquid crystal display or a reflectiveliquid crystal display, some or all of pixel electrodes may function asreflective electrodes. For example, some or all of pixel electrodes areformed to contain aluminum, silver, or the like. In such a case, amemory circuit such as an SRAM can be further provided under thereflective electrodes. Accordingly, power consumption can be furtherreduced.

For example, in this specification and the like, an active-matrix methodin which an active element (a non-linear element) is included in a pixelor a passive-matrix method in which an active element is not included ina pixel can be used.

In the active-matrix method, as an active element, not only a transistorbut also a variety of active elements can be used. For example, an MIM(Metal Insulator Metal), a TFD (Thin Film Diode), or the like can alsobe used. Since these elements can be formed with a smaller number ofmanufacturing steps, manufacturing cost can be reduced or yield can beimproved. Alternatively, since the size of these elements is small, theaperture ratio can be improved, so that power consumption can be reducedor higher luminance can be achieved.

Since an active element is not used in the passive-matrix type, thenumber of manufacturing steps is small, so that manufacturing cost canbe reduced or yield can be improved. Alternatively, since an activeelement is not used, the aperture ratio can be improved, so that powerconsumption can be reduced or higher luminance can be achieved, forexample.

[Driving Method Example for Touch Panel]

The operation of the touch panel 90, which performs display in the firstmode for moving image display and in the second mode for still imagedisplay, will be described below with reference to a timing chart inFIG. 26. FIG. 26 illustrates the signal waveforms of the verticalsynchronization signal (Vsync) and a data signal (Vdata) that is outputto the source line L_Y from the source driver 903.

FIG. 26 is an example of a timing chart of the touch panel 90 in thecase where moving image display, still image display, and moving imagedisplay are performed in that order. Here, there is motion in image datafor the first to k-th frames. Then, there is no motion in image data forthe (k+1)-th to (k+3)-th frames. Then, there is motion in image data forthe (k+4)-th and subsequent frames. Note that k is an integer of 2 ormore.

In the first moving image display period, the motion detection portion911 determines that there is motion in image data for each frame.Therefore, the touch panel 90 operates in the first mode. The controlcircuit 910 outputs image signals (Video) to the source driver 903 athigher than or equal to the frequency of the vertical synchronizationsignal, here a frame frequency f₁. The source driver 903 continuouslyoutputs data signals (Vdata) to the source line L_Y. Note that thelength of one frame period in the moving image display period isrepresented by 1/f₁ (seconds).

Next, in the still image display period, the motion detection portion911 performs image processing for detecting motion and determines thatthere is no motion in image data for the (k+1)-th frame. Therefore, thetouch panel 90 operates in the second mode. The control circuit 910outputs to the source driver 903 at a frame frequency lower than thefrequency of the vertical synchronization signal, here a frame frequencyf₁. The source driver 903 intermittently outputs data signals (Vdata) tothe source line Ly. Note that the length of one frame period in thestill image display period is represented by 1/f₂ (seconds).

Since the source driver 903 can intermittently output data signals(Vdata), the supply of control signals (e.g., a start pulse signal and aclock signal) to the gate driver 902 and the source driver 903 can alsobe performed intermittently; thus, the gate driver 902 and the sourcedriver 903 can be stopped at regular intervals.

The intermittent output of data signals (Vdata) to the source line L_Yin the second mode will be specifically described. For example, asillustrated in FIG. 26, in the (k+1)-th frame, the control circuit 910outputs control signals to the gate driver 902 and the source driver 903and outputs image signals Video to the source driver 903 at the framefrequency f₂. The source driver 903 outputs the data signal (Vdata)written in the previous period, that is, the data signal (Vdata) outputto the source line L_Y in the k-th frame, to the source line L_Y. Inthis manner, in the still image display period, the data signal (Vdata)written in the previous period is repeatedly written to the source lineL_Y every period of 1/f₂ (seconds). Thus, a voltage corresponding to thegray level of an image signal for the same image can be refreshed.Refresh performed at regular intervals can reduce flickers due to theshift of gray levels caused by a voltage drop and can provide a touchpanel with improved display quality.

The control circuit 910 operates in the second mode until the result ofdetermination that there is motion in image data or the input of asensor signal is obtained in the motion detection portion 911.

Then, when the motion detection portion 911 determines that there ismotion in image data for the (k+4)-th and subsequent frames, the touchpanel 90 operates in the first mode again. The control circuit 910outputs image signals (Video) to the source driver 903 at higher than orequal to the frequency of the vertical synchronization signal, here theframe frequency f₁. The source driver 903 continuously outputs datasignals (Vdata) to the source line L_Y.

The touch panel of one embodiment of the present invention has astructure in which a display device and a touch sensor are sandwichedbetween two flexible substrates, for example, and the distance betweenthe display device and the touch sensor can be extremely reduced. Atthis time, noise caused by driving the display device might be easilytransmitted to the touch sensor, lowering the sensitivity of the touchsensor; by employing the driving method exemplified in this embodiment,a touch panel with both reduced thickness and high detection sensitivitycan be realized.

At least part of this embodiment can be implemented as appropriate incombination with any of the other embodiments described in thisspecification.

EXAMPLE

In this example, an electronic device of one embodiment of the presentinvention was manufactured.

A display panel of the electronic device manufactured in this examplewas manufactured by forming a separation layer (a tungsten film) over aformation substrate (a glass substrate), forming a layer to be separatedwhich included a transistor, a light-emitting element, and the like overthe separation layer, then separating the formation substrate and thelayer to be separated from each other, and attaching a flexiblesubstrate to the separated layer with an adhesive.

As the transistor, a transistor using a CAAC-OS (C Axis AlignedCrystalline Oxide Semiconductor) was used. Unlike an amorphous one, theCAAC-OS has few defect states and can improve the reliability of thetransistor. Moreover, since the CAAC-OS is characterized in that a grainboundary is not observed, a stable and uniform film can be formed over alarge area and stress that is caused by curving a flexiblelight-emitting device does not easily make a crack in a CAAC-OS film.

The CAAC-OS refers to a crystalline oxide semiconductor having c-axisalignment of crystals in a direction substantially perpendicular to thefilm surface. It has been confirmed that oxide semiconductors have avariety of crystal structures other than a single crystal, for example,a nano-crystal (nc), which is an aggregate of nanoscale microcrystals.The crystallinity of the CAAC-OS is lower than that of a single crystaland higher than that of an nc.

In this example, a channel-etched transistor using an In—Ga—Zn-basedoxide was used. The transistor was manufactured over a glass substratethrough a process at lower than 500° C.

In a method of manufacturing an element such as a transistor directlyover an organic resin such as a plastic substrate, the temperature ofthe process for manufacturing the element needs to be lower than theupper temperature limit of the organic resin. In this example, theformation substrate is a glass substrate and the separation layer, whichis an inorganic film, has high heat resistance; thus, the transistor canbe manufactured at the same temperature as in the case where atransistor is manufactured over a glass substrate, and the performanceand reliability of the transistor can be easily secured.

As the light-emitting element, a white-light-emitting tandem (stacked)organic EL element was used. The light-emitting element has atop-emission structure, and light from the light-emitting element isextracted to the outside of the display panel through a color filter.

In the manufactured display panel, the diagonal size of a displayportion is 5.9 inches, the number of pixels is 720×1280, the pixel sizeis 102 μm×102 the resolution is 249 ppi, and the aperture ratio is45.2%. In addition, the frame frequency is 60 Hz, a scan driver wasintegrated, and a source driver was mounted by a COF method. Themanufactured display panel had a thickness of 100 μm or less and aweight of approximately 3 g.

FIGS. 27A, 27B, and 27C show photographs of the manufactured electronicdevice. FIG. 27A shows a state where a display surface of the displaypanel is planar, FIG. 27B shows a state in the middle of folding thedisplay panel, and FIG. 27C shows a state where the display panel isfolded. Note that reference numerals and the like are omitted in FIGS.27B and 27C for clarity.

The electronic device shown in FIG. 27A and the like includes thedisplay panel 101, the support body 142 a, the support body 142 b, thesupport body 142 c, the hinge 143 a, and the hinge 143 b. In addition,the support body 142 b has a mechanism with which the length betweenboth ends thereof changes (a slide mechanism 165).

In this manner, the electronic device of one embodiment of the presentinvention can be easily changed in shape from the state where thedisplay surface of the display panel 101 is planar into the state whereit is folded without damage to the display panel 101.

The above is the description of the example.

At least part of this example can be implemented as appropriate incombination with any of the embodiments described in this specification.

REFERENCE NUMERALS

-   100 electronic device-   101 display panel-   101 a portion-   101 b portion-   101 c portion-   102 a support body-   102 b support body-   102 c support body-   103 hinge-   103 a hinge-   103 b hinge-   110 hinge-   110 a plane-   110 b plane-   111 rotation axis-   111 a rotation axis-   111 b rotation axis-   120 electronic device-   121 electrode-   122 electrode-   130 electronic device-   140 electronic device-   141 housing-   142 a support body-   142 b support body-   142 c support body-   143 a hinge-   143 b hinge-   144 printed board-   145 operation button-   147 FPC-   148 terminal connection portion-   149 battery-   151 a rotation axis-   151 b rotation axis-   160 electronic device-   161 housing-   162 a member-   162 b member-   162 c member-   163 screw-   164 opening-   201 formation substrate-   203 separation layer-   205 formation substrate-   207 separation layer-   230 light-emitting element-   301 display portion-   302 pixel-   302B sub-pixel-   302G sub-pixel-   302R sub-pixel-   302 t transistor-   303 c capacitor-   303 g(1) scan line driver circuit-   303 g(2) imaging pixel driver circuit-   303 s(1) image signal line driver circuit-   303 s(2) imaging signal line driver circuit-   303 t transistor-   304 gate-   308 imaging pixel-   308 p photoelectric conversion element-   308 t transistor-   309 FPC-   311 wiring-   319 terminal-   321 insulating layer-   328 partition-   329 spacer-   350R light-emitting element-   351R lower electrode-   352 upper electrode-   353 EL layer-   353 a EL layer-   353 b EL layer-   354 intermediate layer-   360 sealing layer-   367BM light-blocking layer-   367 p anti-reflective layer-   367R coloring layer-   380B light-emitting module-   380G light-emitting module-   380R light-emitting module-   390 touch panel-   501 display portion-   502R sub-pixel-   502 t transistor-   503 c capacitor-   503 g scan line driver circuit-   503 t transistor-   505 touch panel-   505B touch panel-   509 FPC-   510 substrate-   510 a insulating layer-   510 b flexible substrate-   510 c adhesive layer-   511 wiring-   519 terminal-   521 insulating film-   528 partition-   550R light-emitting element-   560 sealing layer-   567BM light-blocking layer-   567 p anti-reflective layer-   567R coloring layer-   570 substrate-   570 a insulating layer-   570 b flexible substrate-   570 c adhesive layer-   580R light-emitting module-   590 substrate-   591 electrode-   592 electrode-   593 insulating layer-   594 wiring-   595 touch sensor-   597 adhesive layer-   598 wiring-   599 connection layer-   601 pulse voltage output circuit-   602 current detection circuit-   603 capacitor-   611 transistor-   612 transistor-   613 transistor-   621 electrode-   622 electrode-   801 substrate-   803 substrate-   804 light-emitting portion-   806 driver circuit portion-   808 FPC-   811 adhesive layer-   813 insulating layer-   814 conductive layer-   815 insulating layer-   816 conductive layer-   817 insulating layer-   817 a insulating layer-   817 b insulating layer-   820 transistor-   821 insulating layer-   822 transistor-   823 sealing layer-   824 sealing layer-   825 connector-   827 spacer-   830 light-emitting element-   831 lower electrode-   833 EL layer-   835 upper electrode-   841 adhesive layer-   843 insulating layer-   845 coloring layer-   847 light-blocking layer-   849 overcoat-   857 conductive layer-   857 a conductive layer-   857 b conductive layer-   90 touch panel-   900 display device-   901 display portion-   902 gate driver-   903 source driver-   904 D-A conversion circuit-   910 control circuit-   911 detection portion-   920 counter circuit-   950 touch sensor

This application is based on Japanese Patent Application Ser. No.2014-039372 filed with Japan Patent Office on Feb. 28, 2014 and JapanesePatent Application Ser. No. 2014-218932 filed with Japan Patent Officeon Oct. 28, 2014, the entire contents of which are hereby incorporatedby reference.

What is claimed is:
 1. An electronic device comprising a first support body, a second support body, a first hinge, and a display panel, wherein the display panel comprises a first portion supported by the first support body, a second portion supported by the second support body, and a third portion that is positioned between the first portion and the second portion and has flexibility, wherein the display panel comprises a display surface overlapping with the first portion, the second portion, and the third portion, wherein the first hinge has a first rotation axis and has a function of connecting the first support body and the second support body to each other, wherein the first support body and the second support body have a function of relatively rotating on the first rotation axis, wherein the first rotation axis and a first plane including the display surface overlapping with the first portion are parallel to each other, wherein the first rotation axis and a second plane including the display surface overlapping with the second portion are parallel to each other, wherein a distance between the first plane and the first rotation axis is greater than zero, and wherein a distance between the second plane and the first rotation axis is greater than zero. 